Глава 16. MySQL Cluster NDB 7.2

Содержание

16.1. MySQL Cluster Overview
16.1.1. MySQL Cluster Core Concepts
16.1.2. MySQL Cluster Nodes, Node Groups, Replicas, and Partitions
16.1.3. MySQL Cluster Hardware, Software, and Networking Requirements
16.1.4. MySQL Cluster Development History
16.1.5. MySQL Server using InnoDB Compared with MySQL Cluster
16.1.6. Known Limitations of MySQL Cluster
16.2. MySQL Cluster Installation
16.2.1. Installing MySQL Cluster on Linux
16.2.2. Installing MySQL Cluster on Windows
16.2.3. Initial Configuration of MySQL Cluster
16.2.4. Initial Startup of MySQL Cluster
16.2.5. MySQL Cluster Пример with Tables and Data
16.2.6. Safe Shutdown and Restart of MySQL Cluster
16.2.7. Upgrading and Downgrading MySQL Cluster NDB 7.2
16.3. MySQL Cluster Configuration
16.3.1. Quick Test Setup of MySQL Cluster
16.3.2. MySQL Cluster Configuration Files
16.3.3. Overview of MySQL Cluster Configuration Parameters
16.3.4. MySQL Server Options and Variables for MySQL Cluster
16.3.5. Using High-Speed Interconnects with MySQL Cluster
16.4. MySQL Cluster Programs
16.4.1. MySQL Server Usage for MySQL Cluster
16.4.2. ndbd — The MySQL Cluster Data Node Daemon
16.4.3. ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)
16.4.4. ndb_mgmd — The MySQL Cluster Management Server Daemon
16.4.5. ndb_mgm — The MySQL Cluster Management Client
16.4.6. ndb_config — Extract MySQL Cluster Configuration Information
16.4.7. ndb_cpcd — Automate Testing for NDB Development
16.4.8. ndb_delete_all — Delete All Rows from an NDB Table
16.4.9. ndb_desc — Describe NDB Tables
16.4.10. ndb_drop_index — Drop Index from an NDB Table
16.4.11. ndb_drop_table — Drop an NDB Table
16.4.12. ndb_error_reporter — NDB Error-Reporting Utility
16.4.13. ndb_print_backup_file — Print NDB Backup File Contents
16.4.14. ndb_print_schema_file — Print NDB Schema File Contents
16.4.15. ndb_print_sys_file — Print NDB System File Contents
16.4.16. ndbd_redo_log_reader — Check and Print Content of Cluster Redo Log
16.4.17. ndb_restore — Restore a MySQL Cluster Backup
16.4.18. ndb_select_all — Print Rows from an NDB Table
16.4.19. ndb_select_count — Print Row Counts for NDB Tables
16.4.20. ndb_show_tables — Display List of NDB Tables
16.4.21. ndb_size.pl — NDBCLUSTER Size Requirement Estimator
16.4.22. ndb_waiter — Wait for MySQL Cluster to Reach a Given Status
16.4.23. Options Common to MySQL Cluster Programs
16.5. Management of MySQL Cluster
16.5.1. Summary of MySQL Cluster Start Phases
16.5.2. Commands in the MySQL Cluster Management Client
16.5.3. Online Backup of MySQL Cluster
16.5.4. Performing a Rolling Restart of a MySQL Cluster
16.5.5. Event Reports Generated in MySQL Cluster
16.5.6. MySQL Cluster Log Messages
16.5.7. MySQL Cluster Single User Mode
16.5.8. Quick Reference: MySQL Cluster SQL Statements
16.5.9. The ndbinfo MySQL Cluster Information Database
16.5.10. MySQL Cluster Security Issues
16.5.11. MySQL Cluster Disk Data Tables
16.5.12. Adding MySQL Cluster Data Nodes Online
16.5.13. Distributed MySQL Privileges for MySQL Cluster
16.5.14. NDB API Statistics Counters and Variables
16.5.15. ndbmemcache
16.6. MySQL Cluster Replication
16.6.1. MySQL Cluster Replication: Abbreviations and Symbols
16.6.2. General Requirements for MySQL Cluster Replication
16.6.3. Known Issues in MySQL Cluster Replication
16.6.4. MySQL Cluster Replication Schema and Tables
16.6.5. Preparing the MySQL Cluster for Replication
16.6.6. Starting MySQL Cluster Replication (Single Replication Channel)
16.6.7. Using Two Replication Channels for MySQL Cluster Replication
16.6.8. Implementing Failover with MySQL Cluster Replication
16.6.9. MySQL Cluster Backups With MySQL Cluster Replication
16.6.10. MySQL Cluster Replication: Multi-Master and Circular Replication
16.6.11. MySQL Cluster Replication Conflict Resolution
16.7. Changes in MySQL Cluster
16.7.1. Changes in MySQL Cluster NDB 7.2

This chapter contains information about MySQL Cluster, which is a high-availability, high-redundancy version of MySQL adapted for the distributed computing environment. Recent releases of MySQL Cluster use version 7 of the NDBCLUSTER storage engine (also known as NDB) to enable running several computers with MySQL servers and other software in a cluster; the latest releases available for production use incorporate NDB version 7.2.

Support for the NDBCLUSTER storage engine is not included in the standard MySQL Server 5.5 binaries built by Oracle. Instead, users of MySQL Cluster binaries from Oracle should upgrade to the most recent binary release of MySQL Cluster for supported platforms—these include RPMs that should work with most Linux distributions. MySQL Cluster users who build from source should use the sources provided for MySQL Cluster. (Locations where the sources can be obtained are listed later in this section.)

This chapter contains information about MySQL Cluster NDB 7.2 releases through 5.5.20-ndb-7.2.5. Currently, the MySQL Cluster NDB 7.2 release series is Generally Available (GA), as is MySQL Cluster NDB 7.1. MySQL Cluster NDB 7.0 and MySQL Cluster NDB 6.3 are previous GA release series; although they are still supported, we recommend that new deployments use MySQL Cluster NDB 7.2. For information about MySQL Cluster NDB 7.1, MySQL Cluster NDB 7.0, and previous versions of MySQL Cluster, see MySQL Cluster NDB 6.X/7.X, in the MySQL 5.1 Manual.

Supported Platforms.  MySQL Cluster is currently available and supported on a number of platforms. For exact levels of support available for on specific combinations of operating system versions, operating system distributions, and hardware platforms, please refer to http://www.mysql.com/support/supportedplatforms/cluster.html.

Availability.  MySQL Cluster binary and source packages are available for supported platforms from http://dev.mysql.com/downloads/cluster/.

MySQL Cluster release numbers.  MySQL Cluster follows a somewhat different release pattern from the mainline MySQL Server 5.5 series of releases. In this Manual and other MySQL documentation, we identify these and later MySQL Cluster releases employing a version number that begins with “NDB”. This version number is that of the NDBCLUSTER storage engine used in the release, and not of the MySQL server version on which the MySQL Cluster release is based.

Version strings used in MySQL Cluster software.  The version string displayed by MySQL Cluster programs uses this format:

mysql-mysql_server_version-ndb-ndb_engine_version

mysql_server_version represents the version of the MySQL Server on which the MySQL Cluster release is based. For all MySQL Cluster NDB 6.x and 7.x releases, this is “5.1”. ndb_engine_version is the version of the NDB storage engine used by this release of the MySQL Cluster software. You can see this format used in the mysql client, as shown here:

shell> mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.1.61-ndb-7.1.20 Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SELECT VERSION()\G
*************************** 1. row ***************************
VERSION(): 5.1.61-ndb-7.1.20
1 row in set (0.00 sec)

This version string is also displayed in the output of the SHOW command in the ndb_mgm client:

ndb_mgm> SHOW
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]     2 node(s)
id=1    @10.0.10.6  (5.5.20-ndb-7.2.5, Nodegroup: 0, Master)
id=2    @10.0.10.8  (5.5.20-ndb-7.2.5, Nodegroup: 0)

[ndb_mgmd(MGM)] 1 node(s)
id=3    @10.0.10.2  (5.5.20-ndb-7.2.5)

[mysqld(API)]   2 node(s)
id=4    @10.0.10.10  (5.5.20-ndb-7.2.5)
id=5 (not connected, accepting connect from any host)

The version string identifies the mainline MySQL version from which the MySQL Cluster release was branched and the version of the NDBCLUSTER storage engine used. For example, the full version string for MySQL Cluster NDB 7.2.4 (the first MySQL Cluster production release based on MySQL Server 5.5) is mysql-5.5.19-ndb-7.2.4. From this we can determine the following:

  • Since the portion of the version string preceding “-ndb-” is the base MySQL Server version, this means that MySQL Cluster NDB 7.2.4 derives from the MySQL 5.5.19, and contains all feature enhancements and bugfixes from MySQL 5.5 up to and including MySQL 5.5.19.

  • Since the portion of the version string following “-ndb-” represents the version number of the NDB (or NDBCLUSTER) storage engine, MySQL Cluster NDB 7.2.4 uses version 7.2.4 of the NDBCLUSTER storage engine.

New MySQL Cluster releases are numbered according to updates in the NDB storage engine, and do not necessarily correspond in a one-to-one fashion with mainline MySQL Server releases. For example, MySQL Cluster NDB 7.2.4 (as previously noted) is based on MySQL 5.5.19, while MySQL Cluster NDB 7.2.0 was based on MySQL 5.1.51 (version string: mysql-5.1.51-ndb-7.2.0).

Compatibility with standard MySQL 5.5 releases.  While many standard MySQL schemas and applications can work using MySQL Cluster, it is also true that unmodified applications and database schemas may be slightly incompatible or have suboptimal performance when run using MySQL Cluster (see Section 16.1.6, “Known Limitations of MySQL Cluster”). Most of these issues can be overcome, but this also means that you are very unlikely to be able to switch an existing application datastore—that currently uses, for example, MyISAM or InnoDB—to use the NDB storage engine without allowing for the possibility of changes in schemas, queries, and applications. In addition, the MySQL Server and MySQL Cluster codebases diverge considerably, so that the standard mysqld cannot function as a drop-in replacement for the version of mysqld supplied with MySQL Cluster.

MySQL Cluster development source trees.  MySQL Cluster development trees can also be accessed from https://code.launchpad.net/~mysql/:

The MySQL Cluster development sources maintained at https://code.launchpad.net/~mysql/ are licensed under the GPL. For information about obtaining MySQL sources using Bazaar and building them yourself, see Section 2.9.3, “Installing MySQL from a Development Source Tree”.

Замечание

As with MySQL Server 5.5, MySQL Cluster NDB 7.2 is built using CMake.

Currently, MySQL Cluster NDB 7.0, MySQL Cluster NDB 7.1, and MySQL Cluster NDB 7.2 releases are all Generally Available (GA), although we recommend that new deployments use MySQL Cluster NDB 7.2. MySQL Cluster NDB 6.1, MySQL Cluster NDB 6.2, and MySQL Cluster NDB 6.3, are no longer in active development. For an overview of major features added in MySQL Cluster NDB 7.2, see Section 16.1.4, “MySQL Cluster Development History”. For an overview of major features added in past MySQL Cluster releases through MySQL Cluster NDB 7.1, see MySQL Cluster Development History.

This chapter represents a work in progress, and its contents are subject to revision as MySQL Cluster continues to evolve. Additional information regarding MySQL Cluster can be found on the MySQL Web site at http://www.mysql.com/products/cluster/.

Additional Resources.  More information may be found in the following places:

16.1. MySQL Cluster Overview

MySQL Cluster is a technology that enables clustering of in-memory databases in a shared-nothing system. The shared-nothing architecture enables the system to work with very inexpensive hardware, and with a minimum of specific requirements for hardware or software.

MySQL Cluster is designed not to have any single point of failure. In a shared-nothing system, each component is expected to have its own memory and disk, and the use of shared storage mechanisms such as network shares, network file systems, and SANs is not recommended or supported.

MySQL Cluster integrates the standard MySQL server with an in-memory clustered storage engine called NDB (which stands for “Network DataBase”). In our documentation, the term NDB refers to the part of the setup that is specific to the storage engine, whereas “MySQL Cluster” refers to the combination of one or more MySQL servers with the NDB storage engine.

A MySQL Cluster consists of a set of computers, known as hosts, each running one or more processes. These processes, known as nodes, may include MySQL servers (for access to NDB data), data nodes (for storage of the data), one or more management servers, and possibly other specialized data access programs. The relationship of these components in a MySQL Cluster is shown here:

MySQL Cluster Components

All these programs work together to form a MySQL Cluster (see Section 16.4, “MySQL Cluster Programs”. When data is stored by the NDB storage engine, the tables (and table data) are stored in the data nodes. Such tables are directly accessible from all other MySQL servers (SQL nodes) in the cluster. Thus, in a payroll application storing data in a cluster, if one application updates the salary of an employee, all other MySQL servers that query this data can see this change immediately.

Although a MySQL Cluster SQL node uses the mysqld server damon, it differs in a number of critical respects from the mysqld binary supplied with the MySQL 5.5 distributions, and the two versions of mysqld are not interchangeable.

In addition, a MySQL server that is not connected to a MySQL Cluster cannot use the NDB storage engine and cannot access any MySQL Cluster data.

The data stored in the data nodes for MySQL Cluster can be mirrored; the cluster can handle failures of individual data nodes with no other impact than that a small number of transactions are aborted due to losing the transaction state. Because transactional applications are expected to handle transaction failure, this should not be a source of problems.

Individual nodes can be stopped and restarted, and can then rejoin the system (cluster). Rolling restarts (in which all nodes are restarted in turn) are used in making configuration changes and software upgrades (see Section 16.5.4, “Performing a Rolling Restart of a MySQL Cluster”). Rolling restarts are also used as part of the process of adding new data nodes online (see Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”). For more information about data nodes, how they are organized in a MySQL Cluster, and how they handle and store MySQL Cluster data, see Section 16.1.2, “MySQL Cluster Nodes, Node Groups, Replicas, and Partitions”.

Backing up and restoring MySQL Cluster databases can be done using the NDB-native functionality found in the MySQL Cluster management client and the ndb_restore program included in the MySQL Cluster distribution. For more information, see Section 16.5.3, “Online Backup of MySQL Cluster”, and Section 16.4.17, “ndb_restore — Restore a MySQL Cluster Backup”. You can also use the standard MySQL functionality provided for this purpose in mysqldump and the MySQL server. See Section 4.5.4, “mysqldump — A Database Backup Program”, for more information.

MySQL Cluster nodes can use a number of different transport mechanisms for inter-node communications, including TCP/IP using standard 100 Mbps or faster Ethernet hardware. It is also possible to use the high-speed Scalable Coherent Interface (SCI) protocol with MySQL Cluster, although this is not required to use MySQL Cluster. SCI requires special hardware and software; see Section 16.3.5, “Using High-Speed Interconnects with MySQL Cluster”, for more about SCI and using it with MySQL Cluster.

16.1.1. MySQL Cluster Core Concepts

NDBCLUSTER (also known as NDB) is an in-memory storage engine offering high-availability and data-persistence features.

The NDBCLUSTER storage engine can be configured with a range of failover and load-balancing options, but it is easiest to start with the storage engine at the cluster level. MySQL Cluster's NDB storage engine contains a complete set of data, dependent only on other data within the cluster itself.

The “Cluster” portion of MySQL Cluster is configured independently of the MySQL servers. In a MySQL Cluster, each part of the cluster is considered to be a node.

Замечание

In many contexts, the term “node” is used to indicate a computer, but when discussing MySQL Cluster it means a process. It is possible to run multiple nodes on a single computer; for a computer on which one or more cluster nodes are being run we use the term cluster host.

There are three types of cluster nodes, and in a minimal MySQL Cluster configuration, there will be at least three nodes, one of each of these types:

  • Management node: The role of this type of node is to manage the other nodes within the MySQL Cluster, performing such functions as providing configuration data, starting and stopping nodes, running backup, and so forth. Because this node type manages the configuration of the other nodes, a node of this type should be started first, before any other node. An MGM node is started with the command ndb_mgmd.

  • Data node: This type of node stores cluster data. There are as many data nodes as there are replicas, times the number of fragments (see Section 16.1.2, “MySQL Cluster Nodes, Node Groups, Replicas, and Partitions”). For example, with two replicas, each having two fragments, you need four data nodes. One replica is sufficient for data storage, but provides no redundancy; therefore, it is recommended to have 2 (or more) replicas to provide redundancy, and thus high availability. A data node is started with the command ndbd (see Section 16.4.2, “ndbd — The MySQL Cluster Data Node Daemon”) or ndbmtd (see Section 16.4.3, “ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)”).

    MySQL Cluster tables are normally stored completely in memory rather than on disk (this is why we refer to MySQL Cluster as an in-memory database). However, some MySQL Cluster data can be stored on disk; see Section 16.5.11, “MySQL Cluster Disk Data Tables”, for more information.

  • SQL node: This is a node that accesses the cluster data. In the case of MySQL Cluster, an SQL node is a traditional MySQL server that uses the NDBCLUSTER storage engine. An SQL node is a mysqld process started with the --ndbcluster and --ndb-connectstring options, which are explained elsewhere in this chapter, possibly with additional MySQL server options as well.

    An SQL node is actually just a specialized type of API node, which designates any application which accesses MySQL Cluster data. Another example of an API node is the ndb_restore utility that is used to restore a cluster backup. It is possible to write such applications using the NDB API. For basic information about the NDB API, see Getting Started with the NDB API.

Important

It is not realistic to expect to employ a three-node setup in a production environment. Such a configuration provides no redundancy; to benefit from MySQL Cluster's high-availability features, you must use multiple data and SQL nodes. The use of multiple management nodes is also highly recommended.

For a brief introduction to the relationships between nodes, node groups, replicas, and partitions in MySQL Cluster, see Section 16.1.2, “MySQL Cluster Nodes, Node Groups, Replicas, and Partitions”.

Configuration of a cluster involves configuring each individual node in the cluster and setting up individual communication links between nodes. MySQL Cluster is currently designed with the intention that data nodes are homogeneous in terms of processor power, memory space, and bandwidth. In addition, to provide a single point of configuration, all configuration data for the cluster as a whole is located in one configuration file.

The management server manages the cluster configuration file and the cluster log. Each node in the cluster retrieves the configuration data from the management server, and so requires a way to determine where the management server resides. When interesting events occur in the data nodes, the nodes transfer information about these events to the management server, which then writes the information to the cluster log.

In addition, there can be any number of cluster client processes or applications. These include standard MySQL clients, NDB-specific API programs, and management clients. These are described in the next few paragraphs.

Standard MySQL clients.  MySQL Cluster can be used with existing MySQL applications written in PHP, Perl, C, C++, Java, Python, Ruby, and so on. Such client applications send SQL statements to and receive responses from MySQL servers acting as MySQL Cluster SQL nodes in much the same way that they interact with standalone MySQL servers.

MySQL clients using a MySQL Cluster as a data source can be modified to take advantage of the ability to connect with multiple MySQL servers to achieve load balancing and failover. For example, Java clients using Connector/J 5.0.6 and later can use jdbc:mysql:loadbalance:// URLs (improved in Connector/J 5.1.7) to achieve load balancing transparently; for more information about using Connector/J with MySQL Cluster, see Using Connector/J with MySQL Cluster.

NDB client programs.  Client programs can be written that access MySQL Cluster data directly from the NDBCLUSTER storage engine, bypassing any MySQL Servers that may connected to the cluster, using the NDB API, a high-level C++ API. Such applications may be useful for specialized purposes where an SQL interface to the data is not needed. For more information, see The NDB API.

Beginning with MySQL Cluster NDB 7.1, NDB-specific Java applications can also be written for MySQL Cluster, using the MySQL Cluster Connector for Java. This MySQL Cluster Connector includes ClusterJ, a high-level database API similar to object-relational mapping persistence frameworks such as Hibernate and JPA that connect directly to NDBCLUSTER, and so does not require access to a MySQL Server. Support is also provided in MySQL Cluster NDB 7.1 and later for ClusterJPA, an OpenJPA implementation for MySQL Cluster that leverages the strengths of ClusterJ and JDBC; ID lookups and other fast operations are performed using ClusterJ (bypassing the MySQL Server), while more complex queries that can benefit from MySQL's query optimizer are sent through the MySQL Server, using JDBC. See Java and MySQL Cluster, and The ClusterJ API and Data Object Model, for more information.

The Memcache API for MySQL Cluster, implemented as the loadable ndbmemcache storage engine for memcached version 1.6 and later, is available beginning with MySQL Cluster NDB 7.2.2. This API can be used to provide a persistent MySQL Cluster data store, accessed using the memcache protocol.

The standard memcached caching engine is included in the MySQL Cluster NDB 7.2 distribution (7.2.2 and later). Each memcached server has direct access to data stored in MySQL Cluster, but is also able to cache data locally and to serve (some) requests from this local cache.

For more information, see Section 16.5.15, “ndbmemcache”.

Management clients.  These clients connect to the management server and provide commands for starting and stopping nodes gracefully, starting and stopping message tracing (debug versions only), showing node versions and status, starting and stopping backups, and so on. An example of this type of program is the ndb_mgm management client supplied with MySQL Cluster (see Section 16.4.5, “ndb_mgm — The MySQL Cluster Management Client”). Such applications can be written using the MGM API, a C-language API that communicates directly with one or more MySQL Cluster management servers. For more information, see The MGM API.

Oracle also makes available MySQL Cluster Manager, which provides an advanced command-line interface simplifying many complex MySQL Cluster management tasks, such restarting a MySQL Cluster with a large number of nodes. The MySQL Cluster Manager client also supports commands for getting and setting the values of most node configuration parameters as well as mysqld server options and variables relating to MySQL Cluster. MySQL Cluster Manager 1.1 provides support for adding data nodes online. See the MySQL Cluster Manager User Manual, for more information.

Event logs.  MySQL Cluster logs events by category (startup, shutdown, errors, checkpoints, and so on), priority, and severity. A complete listing of all reportable events may be found in Section 16.5.5, “Event Reports Generated in MySQL Cluster”. Event logs are of the two types listed here:

  • Cluster log: Keeps a record of all desired reportable events for the cluster as a whole.

  • Node log: A separate log which is also kept for each individual node.

Замечание

Under normal circumstances, it is necessary and sufficient to keep and examine only the cluster log. The node logs need be consulted only for application development and debugging purposes.

Checkpoint.  Generally speaking, when data is saved to disk, it is said that a checkpoint has been reached. More specific to MySQL Cluster, a checkpoint is a point in time where all committed transactions are stored on disk. With regard to the NDB storage engine, there are two types of checkpoints which work together to ensure that a consistent view of the cluster's data is maintained. These are shown in the following list:

  • Local Checkpoint (LCP): This is a checkpoint that is specific to a single node; however, LCP's take place for all nodes in the cluster more or less concurrently. An LCP involves saving all of a node's data to disk, and so usually occurs every few minutes. The precise interval varies, and depends upon the amount of data stored by the node, the level of cluster activity, and other factors.

  • Global Checkpoint (GCP): A GCP occurs every few seconds, when transactions for all nodes are synchronized and the redo-log is flushed to disk.

16.1.2. MySQL Cluster Nodes, Node Groups, Replicas, and Partitions

This section discusses the manner in which MySQL Cluster divides and duplicates data for storage.

A number of concepts central to an understanding of this topic are discussed in the next few paragraphs.

(Data) Node.  An ndbd process, which stores a replica —that is, a copy of the partition (see below) assigned to the node group of which the node is a member.

Each data node should be located on a separate computer. While it is also possible to host multiple ndbd processes on a single computer, such a configuration is not supported.

It is common for the terms “node” and “data node” to be used interchangeably when referring to an ndbd process; where mentioned, management nodes (ndb_mgmd processes) and SQL nodes (mysqld processes) are specified as such in this discussion.

Node Group.  A node group consists of one or more nodes, and stores partitions, or sets of replicas (see next item).

The number of node groups in a MySQL Cluster is not directly configurable; it is a function of the number of data nodes and of the number of replicas (NoOfReplicas configuration parameter), as shown here:

[number_of_node_groups] = number_of_data_nodes / NoOfReplicas

Thus, a MySQL Cluster with 4 data nodes has 4 node groups if NoOfReplicas is set to 1 in the config.ini file, 2 node groups if NoOfReplicas is set to 2, and 1 node group if NoOfReplicas is set to 4. Replicas are discussed later in this section; for more information about NoOfReplicas, see Section 16.3.2.6, “Defining MySQL Cluster Data Nodes”.

Замечание

All node groups in a MySQL Cluster must have the same number of data nodes.

You can add new node groups (and thus new data nodes) online, to a running MySQL Cluster; see Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”, for more information.

Partition.  This is a portion of the data stored by the cluster. There are as many cluster partitions as nodes participating in the cluster. Each node is responsible for keeping at least one copy of any partitions assigned to it (that is, at least one replica) available to the cluster.

A replica belongs entirely to a single node; a node can (and usually does) store several replicas.

NDB and user-defined partitioning.  MySQL Cluster normally partitions NDBCLUSTER tables automatically. However, in MySQL 5.1 and later MySQL Cluster releases, it is possible to employ user-defined partitioning with NDBCLUSTER tables. This is subject to the following limitations:

  1. Only KEY and LINEAR KEY partitioning schemes can be used with NDBCLUSTER tables.

  2. When using ndbd, the maximum number of partitions that may be defined explicitly for any NDBCLUSTER table is 8 * [number of node groups]. (The number of node groups in a MySQL Cluster is determined as discussed previously in this section.)

    When using ndbmtd, this maximum is also affected by the number of local query handler threads, which is determined by the value of the MaxNoOfExecutionThreads configuration parameter. In such cases, the maxmimum number of partitions that may be defined explicitly for an NDB table is equal to 4 * MaxNoOfExecutionThreads * [number of node groups].

    See Section 16.4.3, “ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)”, for more information.

For more information relating to MySQL Cluster and user-defined partitioning, see Section 16.1.6, “Known Limitations of MySQL Cluster”, and Section 17.5.2, “Partitioning Limitations Relating to Storage Engines”.

Replica.  This is a copy of a cluster partition. Each node in a node group stores a replica. Also sometimes known as a partition replica. The number of replicas is equal to the number of nodes per node group.

The following diagram illustrates a MySQL Cluster with four data nodes, arranged in two node groups of two nodes each; nodes 1 and 2 belong to node group 0, and nodes 3 and 4 belong to node group 1. Note that only data (ndbd) nodes are shown here; although a working cluster requires an ndb_mgm process for cluster management and at least one SQL node to access the data stored by the cluster, these have been omitted in the figure for clarity.

A MySQL Cluster, with 2 node groups having 2
        nodes each

The data stored by the cluster is divided into four partitions, numbered 0, 1, 2, and 3. Each partition is stored—in multiple copies—on the same node group. Partitions are stored on alternate node groups as follows:

  • Partition 0 is stored on node group 0; a primary replica (primary copy) is stored on node 1, and a backup replica (backup copy of the partition) is stored on node 2.

  • Partition 1 is stored on the other node group (node group 1); this partition's primary replica is on node 3, and its backup replica is on node 4.

  • Partition 2 is stored on node group 0. However, the placing of its two replicas is reversed from that of Partition 0; for Partition 2, the primary replica is stored on node 2, and the backup on node 1.

  • Partition 3 is stored on node group 1, and the placement of its two replicas are reversed from those of partition 1. That is, its primary replica is located on node 4, with the backup on node 3.

What this means regarding the continued operation of a MySQL Cluster is this: so long as each node group participating in the cluster has at least one node operating, the cluster has a complete copy of all data and remains viable. This is illustrated in the next diagram.

Nodes required to keep a 2x2 cluster
        viable

In this example, where the cluster consists of two node groups of two nodes each, any combination of at least one node in node group 0 and at least one node in node group 1 is sufficient to keep the cluster “alive” (indicated by arrows in the diagram). However, if both nodes from either node group fail, the remaining two nodes are not sufficient (shown by the arrows marked out with an X); in either case, the cluster has lost an entire partition and so can no longer provide access to a complete set of all cluster data.

16.1.3. MySQL Cluster Hardware, Software, and Networking Requirements

One of the strengths of MySQL Cluster is that it can be run on commodity hardware and has no unusual requirements in this regard, other than for large amounts of RAM, due to the fact that all live data storage is done in memory. (It is possible to reduce this requirement using Disk Data tables—see Section 16.5.11, “MySQL Cluster Disk Data Tables”, for more information about these.) Naturally, multiple and faster CPUs can enhance performance. Memory requirements for other MySQL Cluster processes are relatively small.

The software requirements for MySQL Cluster are also modest. Host operating systems do not require any unusual modules, services, applications, or configuration to support MySQL Cluster. For supported operating systems, a standard installation should be sufficient. The MySQL software requirements are simple: all that is needed is a production release of MySQL 5.1.61-ndb-7.0.31 or 5.1.61-ndb-7.1.20 to have MySQL Cluster support. It is not strictly necessary to compile MySQL yourself merely to be able to use MySQL Cluster. We assume that you are using the binaries appropriate to your platform, available from the MySQL Cluster software downloads page at http://dev.mysql.com/downloads/cluster/.

For communication between nodes, MySQL Cluster supports TCP/IP networking in any standard topology, and the minimum expected for each host is a standard 100 Mbps Ethernet card, plus a switch, hub, or router to provide network connectivity for the cluster as a whole. We strongly recommend that a MySQL Cluster be run on its own subnet which is not shared with machines not forming part of the cluster for the following reasons:

  • Security.  Communications between MySQL Cluster nodes are not encrypted or shielded in any way. The only means of protecting transmissions within a MySQL Cluster is to run your MySQL Cluster on a protected network. If you intend to use MySQL Cluster for Web applications, the cluster should definitely reside behind your firewall and not in your network's De-Militarized Zone (DMZ) or elsewhere.

    See Section 16.5.10.1, “MySQL Cluster Security and Networking Issues”, for more information.

  • Efficiency.  Setting up a MySQL Cluster on a private or protected network enables the cluster to make exclusive use of bandwidth between cluster hosts. Using a separate switch for your MySQL Cluster not only helps protect against unauthorized access to MySQL Cluster data, it also ensures that MySQL Cluster nodes are shielded from interference caused by transmissions between other computers on the network. For enhanced reliability, you can use dual switches and dual cards to remove the network as a single point of failure; many device drivers support failover for such communication links.

Network communication and latency.  MySQL Cluster requires communication between data nodes and API nodes (including SQL nodes), as well as between data nodes and other data nodes, to execute queries and updates. Communication latency between these processes can directly affect the observed performance and latency of user queries. In addition, to maintain consistency and service despite the silent failure of nodes, MySQL Cluster uses heartbeating and timeout mechanisms which treat an extended loss of communication from a node as node failure. This can lead to reduced redundancy. Recall that, to maintain data consistency, a MySQL Cluster shuts down when the last node in a node group fails. Thus, to avoid increasing the risk of a forced shutdown, breaks in communication between nodes should be avoided wherever possible.

The failure of a data or API node results in the abort of all uncommitted transactions involving the failed node. Data node recovery requires synchronization of the failed notde's data from a surviving data node, and re-establishment of disk-based redo and checkpoint logs, before the data node returns to service. This recovery can take some time, during which the Cluster operates with reduced redundancy.

Heartbeating relies on timely generation of heartbeat signals by all nodes. This may not be possible if the node is overloaded, has insufficient machine CPU due to sharing with other programs, or is experiencing delays due to swapping. If heartbeat generation is sufficiently delayed, other nodes treat the node that is slow to respond as failed.

This treatment of a slow node as a failed one may or may not be desireable in some circumstances, depending on the impact of the node's slowed operation on the rest of the cluster. When setting timeout values such as HeartbeatIntervalDbDb and HeartbeatIntervalDbApi for MySQL Cluster, care must be taken care to achieve quick detection, failover, and return to service, while avoiding potentially expensive false positives.

Where communication latencies between data nodes are expected to be higher than would be expected in a LAN environment (on the order of 100 µs), timeout parameters must be increased to ensure that any allowed periods of latency periods are well within configured timeouts. Increasing timeouts in this way has a corresponding effect on the worst-case time to detect failure and therefore time to service recovery.

LAN environments can typically be configured with stable low latency, and such that they can provide redundancy with fast failover. Individual link failures can be recovered from with minimal and controlled latency visible at the TCP level (where MySQL Cluster normally operates). WAN environments may offer a range of latencies, as well as redundancy with slower failover times. Individual link failures may require route changes to propagate before end-to-end connectivity is restored. At the TCP level this can appear as large latencies on individual channels. The worst-case observed TCP latency in these scenarios is related to the worst-case time for the IP layer to reroute around the failures.

SCI support.  It is also possible to use the high-speed Scalable Coherent Interface (SCI) with MySQL Cluster, but this is not a requirement. See Section 16.3.5, “Using High-Speed Interconnects with MySQL Cluster”, for more about this protocol and its use with MySQL Cluster.

16.1.4. MySQL Cluster Development History

In this section, we discuss changes in the implementation of MySQL Cluster in MySQL MySQL Cluster NDB 7.2, as compared to MySQL Cluster NDB 7.1 and earlier releases. Changes and features most likely to be of interest are shown in the following table:

MySQL Cluster NDB 7.2
MySQL Cluster NDB 7.2.1 and later MySQL Cluster NDB 7.2 releases are based on MySQL 5.5. For more information about new features in MySQL Server 5.5, see Section 1.4, “What Is New in MySQL 5.5”.
Version 2 binary log row events, to provide support for improvements in MySQL Cluster Replication conflict detection (see next item). A given mysqld can be made to use Version 1 or Version 2 binary logging row events with the --log-bin-use-v1-row-events option.
Two new “primary wins” conflict detection and resolution functions NDB$EPOCH() and NDB$EPOCH_TRANS() for use in replication setups with 2 MySQL Clusters. For more information, see Section 16.6, “MySQL Cluster Replication”.
Distribution of MySQL users and privileges across MySQL Cluster SQL nodes is now supported—see Section 16.5.13, “Distributed MySQL Privileges for MySQL Cluster”.
Improved support for distributed pushed-down joins, which greatly improve performance for many joins that can be executed in parallel on the data nodes.
Default values for a number of data node configuration parameters such as HeartbeatIntervalDbDb and ArbitrationTimeout have been improved.
Support for the Memcache API using the loadable ndbmemcache storage engine. See Section 16.5.15, “ndbmemcache”.

This section contains information about MySQL Cluster NDB 7.2 releases through 5.5.20-ndb-7.2.5, which is currently available for use in production beginning with MySQL Cluster NDB 7.2.4. MySQL Cluster NDB 7.1, MySQL Cluster NDB 7.0, and MySQL Cluster NDB 6.3 are previous GA release series; although these are still supported, we recommend that new deployments use MySQL Cluster NDB 7.2. For information about MySQL Cluster NDB 7.1 and previous releases, see MySQL Cluster NDB 6.X/7.X, in the MySQL 5.1 Manual.

16.1.4.1. MySQL Cluster Development in MySQL Cluster NDB 7.2

The following improvements to MySQL Cluster have been made in MySQL Cluster NDB 7.2.

  • Based on MySQL Server 5.5.  Previous MySQL Cluster release series, including MySQL Cluster NDB 7.1, used MySQL 5.1 as a base. Beginning with MySQL Cluster NDB 7.2.1, MySQL Cluster NDB 7.2 is based on MySQL Server 5.5, so that MySQL Cluster users can benefit from MySQL 5.5's improvements in scalability and performance monitoring. As with MySQL 5.5, MySQL Cluster NDB 7.2.1 and later use CMake for configuring and building from source inh place of GNU autotools (used in MySQL 5.1 and MySQL Cluster releases based on MySQL 5.1). For more information about changes and improvements in MySQL 5.5, see Section 1.4, “What Is New in MySQL 5.5”.

  • Conflict detection using GCI Reflection.  MySQL Cluster Replication implements a new “primary wins” conflict detection and resolution mechanism. GCI Reflection applies in two-cluster circulation “active-active” replication setups, tracking the order in which changes are applied on the MySQL Cluster designated as primary relative to changes originating on the other MySQL Cluster (referred to as the secondary). This relative ordering is used to determine whether changes originating on the slave are concurrent with any changes that originate locally, and are therefore potentially in conflict. Two new conflict detection functions are added: When using NDB$EPOCH(), rows that are out of sync on the secondary are realigned with those on the primary; with NDB$EPOCH_TRANS(), this realignment is applied to transactions. For more information, see Section 16.6.11, “MySQL Cluster Replication Conflict Resolution”.

  • Version 2 binary log row events.  A new format for binary log row events, known as Version 2 binary log row events, provides support for improvements in MySQL Cluster Replication conflict detection (see previous item) and is intended to facilitate further improvements in MySQL Replication. You can cause a given mysqld use Version 1 or Version 2 binary logging row events with the --log-bin-use-v1-row-events option. For backwards compatiblity, Version 2 binary log row events are also available in MySQL Cluster NDB 7.0 (7.0.27 and later) and MySQL Cluster NDB 7.1 (7.1.16 and later). However, MySQL Cluster NDB 7.0 and MySQL Cluster NDB 7.1 continue to use Version 1 binary log row events as the default, whereas the default in MySQL Cluster NDB 7.2.1 and later is use Version 2 row events for binary logging.

  • Distribution of MySQL users and privileges.  Automatic distribution of MySQL users and privileges across all SQL nodes in a given MySQL Cluster is now supported. To enable this support, you must first import an SQL script share/mysql/ndb_dist_priv.sql that is included with the MySQL Cluster NDB 7.2 distribution. This script creates several stored procedures which you can use to enable privilege distribution and perform related tasks.

    When a new MySQL Server joins a MySQL Cluster where privilege distribution is in effect, it also participates in the privilege distribution automatically.

    Once privilege distribution is enabled, all changes to the grant tables made on any mysqld attached to the cluster are immediately available on any other attached MySQL Servers. This is true whether the changes are made using CREATE USER, GRANT, or any of the other statements described elsewhere in this Manual (see Section 12.7.1, “Account Management Statements”.) This includes privileges relating to stored routines and views; however, automatic distribution of the views or stored routines themselves is not currently supported.

    For more information, see Section 16.5.13, “Distributed MySQL Privileges for MySQL Cluster”.

  • Distributed pushed-down joins.  Many joins can now be pushed down to the NDB kernel for processing on MySQL Cluster data nodes. Previously, a join was handled in MySQL Cluster by means of repeated accesses of NDB by the SQL node; however, when pushed-down joins are enabled, a pushable join is sent in its entirety to the data nodes, where it can be distributed among the data nodes and executed in parallel on multiple copies of the data, with a single, merged result being returned to mysqld. This can reduce greatly the number of round trips between an SQL node and the data nodes required to handle such a join, leading to greatly improved performance of join processing.

    It is possible to determine when joins can be pushed down to the data nodes by examining the join with EXPLAIN. A number of new system status variables (Ndb_pushed_queries_defined, Ndb_pushed_queries_dropped, Ndb_pushed_queries_executed, and Ndb_pushed_reads) and additions to the counters table (in the ndbinfo information database) can also be helpful in determining when and how well joins are being pushed down.

    More information and examples are available in the description of the ndb_join_pushdown server system variable. See also the description of the status variables referenced in the previous paragraph, as well as Section 16.5.9.3, “The ndbinfo counters Table”.

  • Improved default values for data node configuration parameters.  In order to provide more resiliency to environmental issues and better handling of some potential failure scenarios, and to perform more reliably with increases in memory and other resource requirements brought about by recent improvements in join handling by NDB, the default values for a number of MySQL Cluster data node configuration parameters have been changed. The parameters and changes are described in the following list:

    In addition, the value computed for MaxNoOfLocalScans when this parameter is not set in config.ini has been increased by a factor of 4.

  • Fail-fast data nodes.  Beginning with MySQL Cluster NDB 7.2.1, data nodes handle corrupted tuples in a fail-fast manner by default. This is a change from previous versions of MySQL Cluster where this behavior had to be enabled explicitly by enabling the CrashOnCorruptedTuple configuration parameter. In MySQL Cluster NDB 7.2.1 and later, this parameter is enabled by default and must be explicitly disabled, in which case data nodes merely log a warning whenever they detect a corrupted tuple.

  • Memcache API support (ndbmemcache).  The Memcached server is a distributed in-memory caching server that uses a simple text-based protocol. It is often employed with key-value stores. The Memcache API for MySQL Cluster, available beginning with MySQL Cluster NDB 7.2.2, is implemented as a loadable storage engine for memcached version 1.6 and later. This API can be used to access a persistent MySQL Cluster data store employing the memcache protocol. It is also possible for the memcached server to provide a strictly defined interface to existing MySQL Cluster tables.

    Each memcache server can both cache data locally and access data stored in MySQL Cluster directly. Cacheing policies are configurable. For more information, see Section 16.5.15, “ndbmemcache”.

16.1.5. MySQL Server using InnoDB Compared with MySQL Cluster

MySQL Server offers a number of choices in storage engines. Since both NDBCLUSTER and InnoDB can serve as transactional MySQL storage engines, users of MySQL Server sometimes become interested in MySQL Cluster. They see NDB as a possible alternative or upgrade to the default InnoDB storage engine in MySQL 5.5. While NDB and InnoDB share common characteristics, there are differences in architecture and implementation, so that some existing MySQL Server applications and usage scenarios can be a good fit for MySQL Cluster, but not all of them.

In this section, we discuss and compare some characteristics of the NDB storage engine used by MySQL Cluster NDB 7.2 with InnoDB used in MySQL 5.5. The next few sections provide a technical comparison. In many instances, decisions about when and where to use MySQL Cluster must be made on a case-by-case basis, taking all factors into consideration. While it is beyond the scope of this documentation to provide specifics for every conceivable usage scenario, we also attempt to offer some very general guidance on the relative suitability of some common types of applications for NDB as opposed to InnoDB backends.

Recent MySQL Cluster NDB 7.2 releases use a mysqld based on MySQL 5.5, including support for InnoDB 1.1. While it is possible to use InnoDB tables with MySQL Cluster, such tables are not clustered. It is also not possible to use programs or libraries from a MySQL Cluster NDB 7.2 distribution with MySQL Server 5.5, or the reverse.

While it is also true that some types of common business applications can be run either on MySQL Cluster or on MySQL Server (most likely using the InnoDB storage engine), there are some important architectural and implementation differences. Section 16.1.5.1, “Differences Between the NDB and InnoDB Storage Engines”, provides a summary of the these differences. Due to the differences, some usage scenarios are clearly more suitable for one engine or the other; see Section 16.1.5.2, “NDB and InnoDB Workloads”. This in turn has an impact on the types of applications that better suited for use with NDB or InnoDB. See Section 16.1.5.3, “NDB and InnoDB Feature Usage Summary”, for a comparison of the relative suitability of each for use in common types of database applications.

For information about the relative characteristics of the NDB and MEMORY storage engines, see When to Use MEMORY or MySQL Cluster.

See Глава 13, Storage Engines, for additional information about MySQL storage engines.

16.1.5.1. Differences Between the NDB and InnoDB Storage Engines

The MySQL Cluster NDB storage engine is implemented using a distributed, shared-nothing architecture, which causes it to behave differently from InnoDB in a number of ways. For those unaccustomed to working with NDB, unexpected behaviors can arise due to its distributed nature with regard to transactions, foreign keys, table limits, and other characteristics. These are shown in the following table:

Feature

InnoDB 1.1

MySQL Cluster NDB 7.2

MySQL Server Version

5.5

5.5

InnoDB Version

InnoDB 1.1

InnoDB 1.1

MySQL Cluster Version

N/A

NDB 7.2

Storage Limits

64TB

3TB

(Practical upper limit based on 48 data nodes with 64GB RAM each; can be increased with disk-based data and BLOBs)

Foreign Keys

Yes

No

(Ignored, as with MyISAM)

Transactions

All standard types

READ COMMITTED

MVCC Non-Blocking Reads

Yes

No

Data Compression

Yes

No

(MySQL Cluster checkpoint and backup files can be compressed)

Large Row Support (> 14K)

Supported for VARBINARY, VARCHAR, BLOB, and TEXT columns

Supported for BLOB and TEXT columns only

(Using these types to store very large amounts of data can lower MySQL Cluster performance)

Replication Support

Asynchronous and semi-synchronous replication using MySQL Replication

Automatic synchronous replication within a MySQL Cluster.

Asynchronous replication between MySQL Clusters, using MySQL Replication

Scaleout for Read Operations

Yes (MySQL Replication)

Yes (Automatic partitioning in MySQL Cluster; MySQL Replication)

Scaleout for Write Operations

Requires application-level partitioning (sharding)

Yes (Automatic partitioning in MySQL Cluster is transparent to applications)

High Availability (HA)

Requires additional software

Yes (Designed for 99.999% uptime)

Node Failure Recovery and Failover

Requires additional software

Automatic

(Key element in MySQL Cluster architecture)

Time for Node Failure Recovery

30 seconds or longer

Typically < 1 second

Real-Time Performance

No

Yes (Low latency)

In-Memory Tables

No

Yes

(Some data can optionally be stored on disk; both in-memory and disk data storage are durable)

NoSQL Access to Storage Engine

Native memcached interface in development (see the MySQL Dev Zone article NoSQL to MySQL with Memcached)

Yes

Multiple APIs, including Memcached, Java, JPA, C++, and HTTP/REST

Concurrent and Parallel Writes

Not supported

Up to 48 writers, optimized for concurrent writes

Conflict Detection and Resolution (Multiple Replication Masters)

No

Yes

Hash Indexes

No

Yes

Online Addition of Nodes

Read-only replicas using MySQL Replication

Yes (all node types)

Online Upgrades

No

Yes

Online Schema Modifications

No

Yes

Real-Time Performance

No

Yes

16.1.5.2. NDB and InnoDB Workloads

MySQL Cluster has a range of unique attributes that make it ideal to serve applications requiring high availability, fast failover, high throughput, and low latency. Due to its distributed architecture and multi-node implementation, MySQL Cluster also has specific constraints that may keep some workloads from performing well. A number of major differences in behavior between the NDB and InnoDB storage engines with regard to some common types of database-driven application workloads are shown in the following table::

Workload

InnoDB

MySQL Cluster (NDB)

High-Volume OLTP Applications

Yes

Yes

DSS Applications (data marts, analytics)

Yes

Limited (Join operations across OLTP datasets not exceeding 3TB in size)

Custom Applications

Yes

Yes

Packaged Applications

Yes

Limited (should be mostly primary key access, without any requirement for foreign keys)

In-Network Telecoms Applications (HLR, HSS, SDP)

No

Yes

Session Management and Caching

Yes

Yes

E-Commerce Applications

Yes

Yes

User Profile Management, AAA Protocol

Yes

Yes

16.1.5.3. NDB and InnoDB Feature Usage Summary

When comparing application feature requirements to the capabilities of InnoDB with NDB, some are clearly more compatible with one storage engine than the other. For example, since NDB does not support foreign keys, an application that requires them and cannot be re-engineered to remove this requirement is likely not to be a good match for MySQL Cluster.

The following table shows required supported features for applications according to which of these two storage engines each of them is usually better suited:

Preferred application requirements for InnoDB

Preferred application requirements for NDB

  • Foreign keys

  • Full table scans

  • Very large databases, rows, or transactions

  • Transactions other than READ COMMITTED

16.1.6. Known Limitations of MySQL Cluster

In the sections that follow, we discuss known limitations in current releases of MySQL Cluster as compared with the features available when using the MyISAM and InnoDB storage engines. If you check the “Cluster” category in the MySQL bugs database at http://bugs.mysql.com, you can find known bugs in the following categories under “MySQL Server:” in the MySQL bugs database at http://bugs.mysql.com, which we intend to correct in upcoming releases of MySQL Cluster:

  • MySQL Cluster

  • Cluster Direct API (NDBAPI)

  • Cluster Disk Data

  • Cluster Replication

  • ClusterJ

This information is intended to be complete with respect to the conditions just set forth. You can report any discrepancies that you encounter to the MySQL bugs database using the instructions given in Section 1.7, “How to Report Bugs or Problems”. If we do not plan to fix the problem in MySQL Cluster NDB 6.X or 7.X, we will add it to the list.

See Section 16.1.6.11, “Previous MySQL Cluster Issues Resolved in MySQL 5.1, MySQL Cluster NDB 6.x, and MySQL Cluster NDB 7.x” for a list of issues in MySQL Cluster in MySQL 5.1 that have been resolved in the current version.

Замечание

Limitations and other issues specific to MySQL Cluster Replication are described in Section 16.6.3, “Known Issues in MySQL Cluster Replication”.

16.1.6.1. Noncompliance with SQL Синтаксис in MySQL Cluster

Some SQL statements relating to certain MySQL features produce errors when used with NDB tables, as described in the following list:

  • Temporary tables.  Temporary tables are not supported. Trying either to create a temporary table that uses the NDB storage engine or to alter an existing temporary table to use NDB fails with the error Table storage engine 'ndbcluster' does not support the create option 'TEMPORARY'.

  • Indexes and keys in NDB tables.  Keys and indexes on MySQL Cluster tables are subject to the following limitations:

    • Column width.  Attempting to create an index on an NDB table column whose width is greater than 3072 bytes succeeds, but only the first 3072 bytes are actually used for the index. In such cases, a warning Specified key was too long; max key length is 3072 bytes is issued, and a SHOW CREATE TABLE statement shows the length of the index as 3072.

    • TEXT and BLOB columns.  You cannot create indexes on NDB table columns that use any of the TEXT or BLOB data types.

    • FULLTEXT indexes.  The NDB storage engine does not support FULLTEXT indexes, which are possible for MyISAM tables only.

      However, you can create indexes on VARCHAR columns of NDB tables.

    • USING HASH keys and NULL Using nullable columns in unique keys and primary keys means that queries using these columns are handled as full table scans. To work around this issue, make the column NOT NULL, or re-create the index without the USING HASH option.

    • Prefixes.  There are no prefix indexes; only entire columns can be indexed. (The size of an NDB column index is always the same as the width of the column in bytes, up to and including 3072 bytes, as described earlier in this section. Also see Section 16.1.6.6, “Unsupported or Missing Features in MySQL Cluster”, for additional information.)

    • BIT columns.  A BIT column cannot be a primary key, unique key, or index, nor can it be part of a composite primary key, unique key, or index.

    • AUTO_INCREMENT columns.  Like other MySQL storage engines, the NDB storage engine can handle a maximum of one AUTO_INCREMENT column per table. However, in the case of a Cluster table with no explicit primary key, an AUTO_INCREMENT column is automatically defined and used as a “hidden” primary key. For this reason, you cannot define a table that has an explicit AUTO_INCREMENT column unless that column is also declared using the PRIMARY KEY option. Attempting to create a table with an AUTO_INCREMENT column that is not the table's primary key, and using the NDB storage engine, fails with an error.

  • MySQL Cluster and geometry data types.  Geometry data types (WKT and WKB) are supported for NDB tables. However, spatial indexes are not supported.

  • Character sets and binary log files.  Currently, the ndb_apply_status and ndb_binlog_index tables are created using the latin1 (ASCII) character set. Because names of binary logs are recorded in this table, binary log files named using non-Latin characters are not referenced correctly in these tables. This is a known issue, which we are working to fix. (Bug #50226)

    To work around this problem, use only Latin-1 characters when naming binary log files or setting any the --basedir, --log-bin, or --log-bin-index options.

  • Creating NDBCLUSTER tables with user-defined partitioning.  Support for user-defined partitioning for MySQL Cluster in MySQL 5.1 (including MySQL Cluster NDB 6.X and 7.X through 7.1) is restricted to [LINEAR] KEY partitioning. Beginning with MySQL 5.1.12, using any other partitioning type with ENGINE=NDB or ENGINE=NDBCLUSTER in a CREATE TABLE statement results in an error.

    Default partitioning scheme.  As of MySQL 5.1.6, all MySQL Cluster tables are by default partitioned by KEY using the table's primary key as the partitioning key. If no primary key is explicitly set for the table, the “hidden” primary key automatically created by the NDBCLUSTER storage engine is used instead. For additional discussion of these and related issues, see Section 17.2.5, “KEY Partitioning”.

    CREATE TABLE and ALTER TABLE statements that would cause a user-partitioned NDBCLUSTER table not to meet either or both of the following two requirements are not permitted, and fail with an error:

    1. The table must have an explicit primary key.

    2. All columns listed in the table's partitioning expression must be part of the primary key.

    Exception.  If a user-partitioned NDBCLUSTER table is created using an empty column-list (that is, using PARTITION BY [LINEAR] KEY()), then no explicit primary key is required.

    Maximum number of partitions for NDBCLUSTER tables.  The maximum number of partitions that can defined for a NDBCLUSTER table when employing user-defined partitioning is 8 per node group. (See Section 16.1.2, “MySQL Cluster Nodes, Node Groups, Replicas, and Partitions”, for more information about MySQL Cluster node groups.

    DROP PARTITION not supported.  It is not possible to drop partitions from NDB tables using ALTER TABLE ... DROP PARTITION. The other partitioning extensions to ALTER TABLEADD PARTITION, REORGANIZE PARTITION, and COALESCE PARTITION—are supported for Cluster tables, but use copying and so are not optimized. See Section 17.3.1, “Management of RANGE and LIST Partitions” and Section 12.1.7, “ALTER TABLE Синтаксис”.

  • Row-based replication.  When using row-based replication with MySQL Cluster, binary logging cannot be disabled. That is, the NDB storage engine ignores the value of sql_log_bin. (Bug #16680)

16.1.6.2. Limits and Differences of MySQL Cluster from Standard MySQL Limits

In this section, we list limits found in MySQL Cluster that either differ from limits found in, or that are not found in, standard MySQL.

Memory usage and recovery.  Memory consumed when data is inserted into an NDB table is not automatically recovered when deleted, as it is with other storage engines. Instead, the following rules hold true:

16.1.6.3. Limits Relating to Transaction Handling in MySQL Cluster

A number of limitations exist in MySQL Cluster with regard to the handling of transactions. These include the following:

  • Transaction isolation level.  The NDBCLUSTER storage engine supports only the READ COMMITTED transaction isolation level. (InnoDB, for example, supports READ COMMITTED, READ UNCOMMITTED, REPEATABLE READ, and SERIALIZABLE.) See Section 16.5.3.4, “MySQL Cluster Backup Troubleshooting”, for information on how this can affect backing up and restoring Cluster databases.)

  • Transactions and BLOB or TEXT columns.  NDBCLUSTER stores only part of a column value that uses any of MySQL's BLOB or TEXT data types in the table visible to MySQL; the remainder of the BLOB or TEXT is stored in a separate internal table that is not accessible to MySQL. This gives rise to two related issues of which you should be aware whenever executing SELECT statements on tables that contain columns of these types:

    1. For any SELECT from a MySQL Cluster table: If the SELECT includes a BLOB or TEXT column, the READ COMMITTED transaction isolation level is converted to a read with read lock. This is done to guarantee consistency.

    2. For any SELECT which uses a unique key lookup to retrieve any columns that use any of the BLOB or TEXT data types and that is executed within a transaction, a shared read lock is held on the table for the duration of the transaction—that is, until the transaction is either committed or aborted.

      This issue does not occur for queries that use index or table scans, even against NDB tables having BLOB or TEXT columns.

      For example, consider the table t defined by the following CREATE TABLE statement:

      CREATE TABLE t (
          a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
          b INT NOT NULL,
          c INT NOT NULL,
          d TEXT,
          INDEX i(b),
          UNIQUE KEY u(c)
      ) ENGINE = NDB,

      Either of the following queries on t causes a shared read lock, because the first query uses a primary key lookup and the second uses a unique key lookup:

      SELECT * FROM t WHERE a = 1;
      
      SELECT * FROM t WHERE c = 1;

      However, none of the four queries shown here causes a shared read lock:

      SELECT * FROM t WHERE b 1;
      
      SELECT * FROM t WHERE d = '1';
      
      SELECT * FROM t;
      
      SELECT b,c WHERE a = 1; 

      This is because, of these four queries, the first uses an index scan, the second and third use table scans, and the fourth, while using a primary key lookup, does not retrieve the value of any BLOB or TEXT columns.

      You can help minimize issues with shared read locks by avoiding queries that use unique key lookups that retrieve BLOB or TEXT columns, or, in cases where such queries are not avoidable, by committing transactions as soon as possible afterward.

  • Rollbacks.  There are no partial transactions, and no partial rollbacks of transactions. A duplicate key or similar error causes the entire transaction to be rolled back.

    This behavior differs from that of other transactional storage engines such as InnoDB that may roll back individual statements.

  • Transactions and memory usage.  As noted elsewhere in this chapter, MySQL Cluster does not handle large transactions well; it is better to perform a number of small transactions with a few operations each than to attempt a single large transaction containing a great many operations. Among other considerations, large transactions require very large amounts of memory. Because of this, the transactional behavior of a number of MySQL statements is effected as described in the following list:

    • TRUNCATE TABLE is not transactional when used on NDB tables. If a TRUNCATE TABLE fails to empty the table, then it must be re-run until it is successful.

    • DELETE FROM (even with no WHERE clause) is transactional. For tables containing a great many rows, you may find that performance is improved by using several DELETE FROM ... LIMIT ... statements to “chunk” the delete operation. If your objective is to empty the table, then you may wish to use TRUNCATE TABLE instead.

    • LOAD DATA statements.  LOAD DATA INFILE is not transactional when used on NDB tables.

      Important

      When executing a LOAD DATA INFILE statement, the NDB engine performs commits at irregular intervals that enable better utilization of the communication network. It is not possible to know ahead of time when such commits take place.

      LOAD DATA FROM MASTER is not supported in MySQL Cluster.

    • ALTER TABLE and transactions.  When copying an NDB table as part of an ALTER TABLE, the creation of the copy is nontransactional. (In any case, this operation is rolled back when the copy is deleted.)

  • Transactions and the COUNT() function.  When using MySQL Cluster Replication, it is not possible to guarantee the transactional consistency of the COUNT() function on the slave. In other words, when performing on the master a series of statements (INSERT, DELETE, or both) that changes the number of rows in a table within a single transaction, executing SELECT COUNT(*) FROM table queries on the slave may yield intermediate results. This is due to the fact that SELECT COUNT(...) may perform dirty reads, and is not a bug in the NDB storage engine. (See Bug #31321 for more information.)

16.1.6.4. MySQL Cluster Error Handling

Starting, stopping, or restarting a node may give rise to temporary errors causing some transactions to fail. These include the following cases:

  • Temporary errors.  When first starting a node, it is possible that you may see Error 1204 Temporary failure, distribution changed and similar temporary errors.

  • Ошибки due to node failure.  The stopping or failure of any data node can result in a number of different node failure errors. (However, there should be no aborted transactions when performing a planned shutdown of the cluster.)

In either of these cases, any errors that are generated must be handled within the application. This should be done by retrying the transaction.

See also Section 16.1.6.2, “Limits and Differences of MySQL Cluster from Standard MySQL Limits”.

16.1.6.5. Limits Associated with Database Objects in MySQL Cluster

Some database objects such as tables and indexes have different limitations when using the NDBCLUSTER storage engine:

  • Number of database objects.  The maximum number of all NDB database objects in a single MySQL Cluster—including databases, tables, and indexes—is limited to 20320.

  • Attributes per table.  The maximum number of attributes (that is, columns and indexes) that can belong to a given table is 512.

  • Attributes per key.  The maximum number of attributes per key is 32.

  • Row size.  The maximum permitted size of any one row is 14000 bytes (as of MySQL Cluster NDB 7.0). Each BLOB or TEXT column contributes 256 + 8 = 264 bytes to this total.

  • Number of rows per partition.  A single MySQL Cluster partition can hold a maximum of 46137488 rows. Since the number of partitions is the same as the number of data nodes in the cluster (see Section 16.1.2, “MySQL Cluster Nodes, Node Groups, Replicas, and Partitions”), you can increase the available space for data storage by using more data nodes.

    In MySQL Cluster NDB 7.0 and later MySQL Cluster release series (including MySQL Cluster NDB 7.2), you can increase the number of data nodes in the cluster while the cluster remains in operation. See Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”, for more information.

    It is also possible to increase the number of partitions for NDB tables by using explicit KEY or LINEAR KEY partitioning (see Section 17.2.5, “KEY Partitioning”).

16.1.6.6. Unsupported or Missing Features in MySQL Cluster

A number of features supported by other storage engines are not supported for NDB tables. Trying to use any of these features in MySQL Cluster does not cause errors in or of itself; however, errors may occur in applications that expects the features to be supported or enforced:

  • Foreign key constraints.  The foreign key construct is ignored, just as it is in MyISAM tables.

  • Index prefixes.  Prefixes on indexes are not supported for NDBCLUSTER tables. If a prefix is used as part of an index specification in a statement such as CREATE TABLE, ALTER TABLE, or CREATE INDEX, the prefix is ignored.

  • LOAD TABLE ... FROM MASTER LOAD TABLE FROM MASTER is not supported.

  • Savepoints and rollbacks.  Savepoints and rollbacks to savepoints are ignored as in MyISAM.

  • Durability of commits.  There are no durable commits on disk. Commits are replicated, but there is no guarantee that logs are flushed to disk on commit.

  • Replication.  Statement-based replication is not supported. Use --binlog-format=ROW (or --binlog-format=MIXED) when setting up cluster replication. See Section 16.6, “MySQL Cluster Replication”, for more information.

Замечание

See Section 16.1.6.3, “Limits Relating to Transaction Handling in MySQL Cluster”, for more information relating to limitations on transaction handling in NDB.

16.1.6.7. Limitations Relating to Performance in MySQL Cluster

The following performance issues are specific to or especially pronounced in MySQL Cluster:

  • Range scans.  There are query performance issues due to sequential access to the NDB storage engine; it is also relatively more expensive to do many range scans than it is with either MyISAM or InnoDB.

  • Reliability of Records in range The Records in range statistic is available but is not completely tested or officially supported. This may result in nonoptimal query plans in some cases. If necessary, you can employ USE INDEX or FORCE INDEX to alter the execution plan. See Section 12.2.9.3, “Index Hint Синтаксис”, for more information on how to do this.

  • Unique hash indexes.  Unique hash indexes created with USING HASH cannot be used for accessing a table if NULL is given as part of the key.

16.1.6.8. Issues Exclusive to MySQL Cluster

The following are limitations specific to the NDBCLUSTER storage engine:

  • Machine architecture.  All machines used in the cluster must have the same architecture. That is, all machines hosting nodes must be either big-endian or little-endian, and you cannot use a mixture of both. For example, you cannot have a management node running on a PowerPC which directs a data node that is running on an x86 machine. This restriction does not apply to machines simply running mysql or other clients that may be accessing the cluster's SQL nodes.

  • Binary logging.  MySQL Cluster has the following limitations or restrictions with regard to binary logging:

See also Section 16.1.6.10, “Limitations Relating to Multiple MySQL Cluster Nodes”.

16.1.6.9. Limitations Relating to MySQL Cluster Disk Data Storage

Disk Data object maxmimums and minimums.  Disk data objects are subject to the following maximums and minimums:

  • Maximum number of tablespaces: 232 (4294967296)

  • Maximum number of data files per tablespace: 216 (65536)

  • The theoretical maximum number of extents per tablespace data file is 216 (65536); however, for practical purposes, the recommended maximum number of extents per data file is 215 (32768).

  • Maximum data file size: The theoretical limit is 64G; however, the practical upper limit is 32G. This is equivalent to 32768 extents of 1M each.

    The minimum and maximum possible sizes of extents for tablespace data files are 32K and 2G, respectively. See Section 12.1.18, “CREATE TABLESPACE Синтаксис”, for more information.

Disk Data tables and diskless mode.  Use of Disk Data tables is not supported when running the cluster in diskless mode. Beginning with MySQL 5.1.12, it is prohibited altogether. (Bug #20008)

16.1.6.10. Limitations Relating to Multiple MySQL Cluster Nodes

Multiple SQL nodes.  The following are issues relating to the use of multiple MySQL servers as MySQL Cluster SQL nodes, and are specific to the NDBCLUSTER storage engine:

  • No distributed table locks.  A LOCK TABLES works only for the SQL node on which the lock is issued; no other SQL node in the cluster “sees” this lock. This is also true for a lock issued by any statement that locks tables as part of its operations. (See next item for an example.)

  • ALTER TABLE operations.  ALTER TABLE is not fully locking when running multiple MySQL servers (SQL nodes). (As discussed in the previous item, MySQL Cluster does not support distributed table locks.)

Multiple management nodes.  When using multiple management servers:

  • You must give nodes explicit IDs in connect strings because automatic allocation of node IDs does not work across multiple management servers.

  • When a management server starts, it first checks for any other management server in the same MySQL Cluster, and upon successful connection to the other management server uses its configuration data. This means that the management server --reload and --initial startup options are ignored unless the management server is the only one running. It also means that, when performing a rolling restart of a MySQL Cluster with multiple management nodes, the management server reads its own configuration file if (and only if) it is the only management server running in this MySQL Cluster. See Section 16.5.4, “Performing a Rolling Restart of a MySQL Cluster”, for more information.

Multiple network addresses.  Multiple network addresses per data node are not supported. Use of these is liable to cause problems: In the event of a data node failure, an SQL node waits for confirmation that the data node went down but never receives it because another route to that data node remains open. This can effectively make the cluster inoperable.

Замечание

It is possible to use multiple network hardware interfaces (such as Ethernet cards) for a single data node, but these must be bound to the same address. This also means that it not possible to use more than one [tcp] section per connection in the config.ini file. See Section 16.3.2.8, “MySQL Cluster TCP/IP Connections”, for more information.

16.1.6.11. Previous MySQL Cluster Issues Resolved in MySQL 5.1, MySQL Cluster NDB 6.x, and MySQL Cluster NDB 7.x

A number of limitations and related issues existing in earlier versions of MySQL Cluster have been resolved:

  • Variable-length column support.  The NDBCLUSTER storage engine now supports variable-length column types for in-memory tables.

    Previously, for example, any Cluster table having one or more VARCHAR fields which contained only relatively small values, much more memory and disk space were required when using the NDBCLUSTER storage engine than would have been the case for the same table and data using the MyISAM engine. In other words, in the case of a VARCHAR column, such a column required the same amount of storage as a CHAR column of the same size. In MySQL 5.1, this is no longer the case for in-memory tables, where storage requirements for variable-length column types such as VARCHAR and BINARY are comparable to those for these column types when used in MyISAM tables (see Section 10.5, “Data Type Storage Requirements”).

    Important

    For MySQL Cluster Disk Data tables, the fixed-width limitation continues to apply. See Section 16.5.11, “MySQL Cluster Disk Data Tables”.

  • Replication with MySQL Cluster.  It is now possible to use MySQL replication with Cluster databases. For details, see Section 16.6, “MySQL Cluster Replication”.

    Circular Replication.  Circular replication is also supported with MySQL Cluster, beginning with MySQL 5.1.18. See Section 16.6.10, “MySQL Cluster Replication: Multi-Master and Circular Replication”.

  • auto_increment_increment and auto_increment_offset The auto_increment_increment and auto_increment_offset server system variables are supported for MySQL Cluster Replication.

  • Backup and restore between architectures.  It is possible to perform a Cluster backup and restore between different architectures. Previously—for example—you could not back up a cluster running on a big-endian platform and then restore from that backup to a cluster running on a little-endian system. (Bug #19255)

  • Multiple data nodes, multi-threaded data nodes.  MySQL Cluster NDB 7.2 supports multiple data node processes on a single host as well as multi-threaded data node processes. See Section 16.4.3, “ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)”, for more information.

  • Identifiers.  Formerly (in MySQL 5.0 and earlier), database names, table names and attribute names could not be as long for NDB tables as tables using other storage engines, because attribute names were truncated internally. In MySQL 5.1 and later, names of MySQL Cluster databases, tables, and table columns follow the same rules regarding length as they do for any other storage engine.

  • Length of CREATE TABLE statements.  CREATE TABLE statements may be no more than 4096 characters in length. This limitation affects MySQL 5.1.6, 5.1.7, and 5.1.8 only. (See Bug #17813)

  • IGNORE and REPLACE functionality.  In MySQL 5.1.7 and earlier, INSERT IGNORE, UPDATE IGNORE, and REPLACE were supported only for primary keys, but not for unique keys. It was possible to work around this issue by removing the constraint, then dropping the unique index, performing any inserts, and then adding the unique index again.

    This limitation was removed for INSERT IGNORE and REPLACE in MySQL 5.1.8. (See Bug #17431.)

  • AUTO_INCREMENT columns.  In MySQL 5.1.10 and earlier versions, the maximum number of tables having AUTO_INCREMENT columns—including those belonging to hidden primary keys—was 2048.

    This limitation was lifted in MySQL 5.1.11.

  • Maximum number of cluster nodes.  The total maximum number of nodes in a MySQL Cluster is 255, including all SQL nodes (MySQL Servers), API nodes (applications accessing the cluster other than MySQL servers), data nodes, and management servers. The total number of data nodes and management nodes is 63, of which up to 48 can be data nodes.

    Замечание

    A data node cannot have a node ID greater than 49.

  • Recovery of memory from deleted rows.  Memory can be reclaimed from an NDB table for reuse with any NDB table by employing OPTIMIZE TABLE, subject to the following limitations:

    You can regulate the effects of OPTIMIZE on performance by adjusting the value of the global system variable ndb_optimization_delay, which sets the number of milliseconds to wait between batches of rows being processed by OPTIMIZE. The default value is 10 milliseconds. It is possible to set a lower value (to a minimum of 0), but not recommended. The maximum is 100000 milliseconds (that is, 100 seconds).

  • Number of tables.  The maximum number of NDBCLUSTER tables in a single MySQL Cluster is included in the total maximum number of NDBCLUSTER database objects (20320). (See Section 16.1.6.5, “Limits Associated with Database Objects in MySQL Cluster”.)

  • Adding and dropping of data nodes.  In MySQL Cluster NDB 7.2 (MySQL Cluster NDB 7.0 and later), it is possible to add new data nodes to a running MySQL Cluster by performing a rolling restart, so that the cluster and the data stored in it remain available to applications.

    When planning to increase the number of data nodes in the cluster online, you should be aware of and take into account the following issues:

    • New data nodes can be added online to a MySQL Cluster only as part of a new node group.

    • New data nodes can be added online, but cannot be dropped online. Reducing the number of data nodes requires a system restart of the cluster.

    • As in previous MySQL Cluster releases, it is not possible to change online either the number of replicas (NoOfReplicas configuration parameter) or the number of data nodes per node group. These changes require a system restart.

    • Redistribution of existing cluster data using the new data nodes is not automatic; however, this can be accomplished using simple SQL statements in the mysql client or other MySQL client application once the nodes have been added. During this procedure, it is not possible to perform DDL operations, although DML operations can continue as normal.

      The distribution of new cluster data (that is, data stored in the cluster after the new nodes have been added) uses the new nodes without manual intervention.

    For more information, see Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”.

  • Distribution of MySQL users and privileges.  Previously, MySQL users and privileges created on one SQL node were unique to that SQL node, due to the fact that the MySQL grant tables were restricted to using the MyISAM storage engine. Beginning with MySQL Cluster NDB 7.2.0, it is possible, following installation of the MySQL Cluster software and setup of the desired users and privileges on one SQL node, to convert the grant tables to use NDB and thus to distribute the users and privileges across all SQL nodes connected to the cluster. You can do this by loading and making use of a set of stored procedures defined in an SQL script supplied with the MySQL Cluster distribution. For more information, see Section 16.5.13, “Distributed MySQL Privileges for MySQL Cluster”.

16.2. MySQL Cluster Installation

This section describes the basics for planning, installing, configuring, and running a MySQL Cluster. Whereas the examples in Section 16.3, “MySQL Cluster Configuration” provide more in-depth information on a variety of clustering options and configuration, the result of following the guidelines and procedures outlined here should be a usable MySQL Cluster which meets the minimum requirements for availability and safeguarding of data.

For information about upgrading or downgrading a MySQL Cluster between release versions, see Section 16.2.7, “Upgrading and Downgrading MySQL Cluster NDB 7.2”.

This section covers hardware and software requirements; networking issues; installation of MySQL Cluster; configuration issues; starting, stopping, and restarting the cluster; loading of a sample database; and performing queries.

Assumptions.  The following sections make a number of assumptions regarding the cluster's physical and network configuration. These assumptions are discussed in the next few paragraphs.

Cluster nodes and host computers.  The cluster consists of four nodes, each on a separate host computer, and each with a fixed network address on a typical Ethernet network as shown here:

NodeIP Address
Management node (mgmd)192.168.0.10
SQL node (mysqld)192.168.0.20
Data node "A" (ndbd)192.168.0.30
Data node "B" (ndbd)192.168.0.40

This may be made clearer by the following diagram:

MySQL Cluster Multi-Computer Setup

Network addressing.  In the interest of simplicity (and reliability), this How-To uses only numeric IP addresses. However, if DNS resolution is available on your network, it is possible to use host names in lieu of IP addresses in configuring Cluster. Alternatively, you can use the hosts file (typically /etc/hosts for Linux and other Unix-like operating systems, C:\WINDOWS\system32\drivers\etc\hosts on Windows, or your operating system's equivalent) for providing a means to do host lookup if such is available.

Potential hosts file issues.  A common problem when trying to use host names for Cluster nodes arises because of the way in which some operating systems (including some Linux distributions) set up the system's own host name in the /etc/hosts during installation. Consider two machines with the host names ndb1 and ndb2, both in the cluster network domain. Red Hat Linux (including some derivatives such as CentOS and Fedora) places the following entries in these machines' /etc/hosts files:

#  ndb1 /etc/hosts:
127.0.0.1   ndb1.cluster ndb1 localhost.localdomain localhost
#  ndb2 /etc/hosts:
127.0.0.1   ndb2.cluster ndb2 localhost.localdomain localhost

SUSE Linux (including OpenSUSE) places these entries in the machines' /etc/hosts files:

#  ndb1 /etc/hosts:
127.0.0.1       localhost
127.0.0.2       ndb1.cluster ndb1
#  ndb2 /etc/hosts:
127.0.0.1       localhost
127.0.0.2       ndb2.cluster ndb2

In both instances, ndb1 routes ndb1.cluster to a loopback IP address, but gets a public IP address from DNS for ndb2.cluster, while ndb2 routes ndb2.cluster to a loopback address and obtains a public address for ndb1.cluster. The result is that each data node connects to the management server, but cannot tell when any other data nodes have connected, and so the data nodes appear to hang while starting.

Caution

You cannot mix localhost and other host names or IP addresses in config.ini. For these reasons, the solution in such cases (other than to use IP addresses for all config.ini HostName entries) is to remove the fully qualified host names from /etc/hosts and use these in config.ini for all cluster hosts.

Host computer type.  Each host computer in our installation scenario is an Intel-based desktop PC running a supported operating system installed to disk in a standard configuration, and running no unnecessary services. The core operating system with standard TCP/IP networking capabilities should be sufficient. Also for the sake of simplicity, we also assume that the file systems on all hosts are set up identically. In the event that they are not, you should adapt these instructions accordingly.

Network hardware.  Standard 100 Mbps or 1 gigabit Ethernet cards are installed on each machine, along with the proper drivers for the cards, and that all four hosts are connected through a standard-issue Ethernet networking appliance such as a switch. (All machines should use network cards with the same throughout. That is, all four machines in the cluster should have 100 Mbps cards or all four machines should have 1 Gbps cards.) MySQL Cluster works in a 100 Mbps network; however, gigabit Ethernet provides better performance.

Important

MySQL Cluster is not intended for use in a network for which throughput is less than 100 Mbps or which experiences a high degree of latency. For this reason (among others), attempting to run a MySQL Cluster over a wide area network such as the Internet is not likely to be successful, and is not supported in production.

Sample data.  We use the world database which is available for download from the MySQL Web site (see http://dev.mysql.com/doc/index-other.html). We assume that each machine has sufficient memory for running the operating system, required MySQL Cluster processes, and (on the data nodes) storing the database.

For general information about installing MySQL, see Глава 2, Installing and Upgrading MySQL. For information about installation of MySQL Cluster on Linux and other Unix-like operating systems, see Section 16.2.1, “Installing MySQL Cluster on Linux”. For information about installation of MySQL Cluster on Windows operating systems, see Section 16.2.2, “Installing MySQL Cluster on Windows”.

For general information about MySQL Cluster hardware, software, and networking requirements, see Section 16.1.3, “MySQL Cluster Hardware, Software, and Networking Requirements”.

16.2.1. Installing MySQL Cluster on Linux

This section covers installation of MySQL Cluster on Linux and other Unix-like operating systems. While the next few sections refer to a Linux operating system, the instructions and procedures given there should be easily adaptable to other supported Unix-like platforms.

MySQL Cluster NDB 7.2 is also available for Windows operating systems; for installation and setup instructions specific to Windows, see Section 16.2.2, “Installing MySQL Cluster on Windows”.

Each MySQL Cluster host computer must have the correct executable programs installed. A host running an SQL node must have installed on it a MySQL Server binary (mysqld). Management nodes require the management server daemon (ndb_mgmd); data nodes require the data node daemon (ndbd or ndbmtd). It is not necessary to install the MySQL Server binary on management node hosts and data node hosts. It is recommended that you also install the management client (ndb_mgm) on the management server host.

Installation of MySQL Cluster on Linux can be done using precompiled binaries from Oracle (downloaded as a .tar.gz archive), with RPM packages (also available from Oracle), or from source code. All three of these installation methods are described in the section that follow.

Regardless of the method used, it is still necessary following installation of the MySQL Cluster binaries to create configuration files for all cluster nodes, before you can start the cluster. See Section 16.2.3, “Initial Configuration of MySQL Cluster”.

16.2.1.1. Installing a MySQL Cluster Binary Release on Linux

This section covers the steps necessary to install the correct executables for each type of Cluster node from precompiled binaries supplied by Oracle.

For setting up a cluster using precompiled binaries, the first step in the installation process for each cluster host is to download the latest MySQL Cluster NDB 7.2 binary archive (mysql-cluster-gpl-7.2.5-linux-i686-glibc23.tar.gz) from the MySQL Cluster downloads area. We assume that you have placed this file in each machine's /var/tmp directory. (If you do require a custom binary, see Section 2.9.3, “Installing MySQL from a Development Source Tree”.)

Замечание

After completing the installation, do not yet start any of the binaries. We show you how to do so following the configuration of the nodes (see Section 16.2.3, “Initial Configuration of MySQL Cluster”).

Data nodes and SQL nodes.  On each of the machines designated to host data nodes or SQL nodes, perform the following steps as the system root user:

  1. Check your /etc/passwd and /etc/group files (or use whatever tools are provided by your operating system for managing users and groups) to see whether there is already a mysql group and mysql user on the system. Some OS distributions create these as part of the operating system installation process. If they are not already present, create a new mysql user group, and then add a mysql user to this group:

    shell> groupadd mysql
    shell> useradd -g mysql mysql
    

    The syntax for useradd and groupadd may differ slightly on different versions of Unix, or they may have different names such as adduser and addgroup.

  2. Change location to the directory containing the downloaded file, unpack the archive, and create a symbolic link named mysql to the mysql directory. Note that the actual file and directory names vary according to the MySQL Cluster version number.

    shell> cd /var/tmp
    shell> tar -C /usr/local -xzvf mysql-cluster-gpl-7.1.20-linux-i686-glibc23.tar.gz
    shell> ln -s /usr/local/mysql-cluster-gpl-7.1.20-linux-i686-glibc23 /usr/local/mysql
    
  3. Change location to the mysql directory and run the supplied script for creating the system databases:

    shell> cd mysql
    shell> scripts/mysql_install_db --user=mysql
    
  4. Set the necessary permissions for the MySQL server and data directories:

    shell> chown -R root .
    shell> chown -R mysql data
    shell> chgrp -R mysql .
    

    Note that the data directory on each machine hosting a data node is /usr/local/mysql/data. This piece of information is essential when configuring the management node. (See Section 16.2.3, “Initial Configuration of MySQL Cluster”.)

  5. Copy the MySQL startup script to the appropriate directory, make it executable, and set it to start when the operating system is booted up:

    shell> cp support-files/mysql.server /etc/rc.d/init.d/
    shell> chmod +x /etc/rc.d/init.d/mysql.server
    shell> chkconfig --add mysql.server
    

    (The startup scripts directory may vary depending on your operating system and version—for example, in some Linux distributions, it is /etc/init.d.)

    Here we use Red Hat's chkconfig for creating links to the startup scripts; use whatever means is appropriate for this purpose on your operating system and distribution, such as update-rc.d on Debian.

Remember that the preceding steps must be repeated on each machine where an SQL node is to reside.

Management nodes.  Installation of the management node does not require the mysqld binary. Only the MySQL Cluster management server (ndb_mgmd) is required; you most likely want to install the management client (ndb_mgm) as well. Both of these binaries also be found in the .tar.gz archive. Again, we assume that you have placed this archive in /var/tmp.

As system root (that is, after using sudo, su root, or your system's equivalent for temporarily assuming the system administrator account's privileges), perform the following steps to install ndb_mgmd and ndb_mgm on the Cluster management node host:

  1. Change location to the /var/tmp directory, and extract the ndb_mgm and ndb_mgmd from the archive into a suitable directory such as /usr/local/bin:

    shell> cd /var/tmp
    shell> tar -zxvf mysql-5.1.61-ndb-7.1.20-linux-i686-glibc23.tar.gz
    shell> cd mysql-5.1.61-ndb-7.1.20-linux-i686-glibc23
    shell> cp bin/ndb_mgm* /usr/local/bin
    

    (You can safely delete the directory created by unpacking the downloaded archive, and the files it contains, from /var/tmp once ndb_mgm and ndb_mgmd have been copied to the executables directory.)

  2. Change location to the directory into which you copied the files, and then make both of them executable:

    shell> cd /usr/local/bin
    shell> chmod +x ndb_mgm*
    

In Section 16.2.3, “Initial Configuration of MySQL Cluster”, we create configuration files for all of the nodes in our example MySQL Cluster.

16.2.1.2. Installing MySQL Cluster from RPM

This section covers the steps necessary to install the correct executables for each type of MySQL Cluster node using RPM packages supplied by Oracle.

RPMs are available for both 32-bit and 64-bit Linux platforms. For a MySQL Cluster, three RPMs are required:

  • The Server RPM (for example, MySQL-Cluster-gpl-server-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-server-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-server-7.1.20-0.sles10.i586.rpm), which supplies the core files needed to run a MySQL Server with NDBCLUSTER storage engine support (that is, as a MySQL Cluster SQL node).

    If you do not have your own client application capable of administering a MySQL server, you should also obtain and install the Client RPM (for example, MySQL-Cluster-gpl-client-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-client-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-client-7.1.20-0.sles10.i586.rpm).

  • The Cluster storage engine RPM (for example, MySQL-Cluster-gpl-storage-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-storage-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-storage-7.1.20-0.sles10.i586.rpm), which supplies the MySQL Cluster data node binary (ndbd).

  • The Cluster storage engine management RPM (for example, MySQL-Cluster-gpl-management-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-management-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-management-7.1.20-0.sles10.i586.rpm) which provides the MySQL Cluster management server binary (ndb_mgmd).

In addition, you should also obtain the NDB Cluster - Storage engine basic tools RPM (for example, MySQL-Cluster-gpl-tools-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-tools-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-tools-7.1.20-0.sles10.i586.rpm), which supplies several useful applications for working with a MySQL Cluster. The most important of these is the MySQL Cluster management client (ndb_mgm). The NDB Cluster - Storage engine extra tools RPM (for example, MySQL-Cluster-gpl-extra-6.3.48-0.sles10.i586.rpm, MySQL-Cluster-gpl-extra-7.0.31-0.sles10.i586.rpm, or MySQL-Cluster-gpl-extra-7.1.20-0.sles10.i586.rpm) contains some additional testing and monitoring programs, but is not required to install a MySQL Cluster. (For more information about these additional programs, see Section 16.4, “MySQL Cluster Programs”.)

The MySQL Cluster version number in the RPM file names (shown here as 6.3.48, 7.0.31, or 7.1.20) can vary according to the version which you are actually using. It is very important that all of the Cluster RPMs to be installed have the same version number. The glibc version number (if present), and architecture designation (shown here as i586) should be appropriate to the machine on which the RPM is to be installed.

Data nodes.  On a computer that is to host a cluster data node it is necessary to install only the NDB Cluster - Storage engine RPM. To do so, copy this RPM to the data node host, and run the following command as the system root user, replacing the name shown for the RPM as necessary to match that of the RPM downloaded from the MySQL web site:

shell> rpm -Uhv MySQL-Cluster-gpl-storage-7.1.20-0.sles10.i586.rpm

The previous command installs the MySQL Cluster data node binary (ndbd) in the /usr/sbin directory.

SQL nodes.  On each machine to be used for hosting a cluster SQL node, install the Server RPM by executing the following command as the system root user, replacing the name shown for the RPM as necessary to match the name of the RPM downloaded from the MySQL web site:

shell> rpm -Uhv MySQL-Cluster-gpl-server-7.1.20-0.sles10.i586.rpm

This installs the MySQL server binary (mysqld) in the /usr/sbin directory, as well as all needed MySQL Server support files. It also installs the mysql.server and mysqld_safe startup scripts in /usr/share/mysql and /usr/bin, respectively. The RPM installer should take care of general configuration issues (such as creating the mysql user and group, if needed) automatically.

Замечание

To administer the SQL node (MySQL server), you should also install the Client RPM, as shown here:

shell> rpm -Uhv MySQL-Cluster-gpl-client-7.1.20-0.sles10.i586.rpm

This installs the mysql client program.

Management nodes.  To install the MySQL Cluster management server, it is necessary only to use the NDB Cluster - Storage engine management RPM. Copy this RPM to the computer intended to host the management node, and then install it by running the following command as the system root user (replace the name shown for the RPM as necessary to match that of the Storage engine management RPM downloaded from the MySQL web site):

shell> rpm -Uhv MySQL-Cluster-gpl-management-7.1.20-0.sles10.i586.rpm

This installs the management server binary (ndb_mgmd) to the /usr/sbin directory.

You should also install the NDB management client, which is supplied by the Storage engine basic tools RPM. Copy this RPM to the same computer as the management node, and then install it by running the following command as the system root user (again, replace the name shown for the RPM as necessary to match that of the Storage engine basic tools RPM downloaded from the MySQL web site):

shell> rpm -Uhv MySQL-Cluster-gpl-tools-7.1.20-0.sles10.i586.rpm

The Storage engine basic tools RPM installs the MySQL Cluster management client (ndb_mgm) to the /usr/bin directory.

Замечание

You can also install the Cluster storage engine extra tools RPM, if you wish, as shown here:

shell> rpm -Uhv MySQL-Cluster-gpl-extra-7.1.20-0.sles10.i586.rpm

You may find the extra tools useful; however the Cluster storage engine extra tools RPM is not required to install a working MySQL Cluster.

See Section 2.5.1, “Installing MySQL from RPM Packages on Linux”, for general information about installing MySQL using RPMs supplied by Oracle.

After installing from RPM, you still need to configure the cluster as discussed in Section 16.2.3, “Initial Configuration of MySQL Cluster”.

16.2.1.3. Building MySQL Cluster from Source on Linux

This section provides information about compiling MySQL Clusteron Linux and other Unix-like platforms. Building MySQL Cluster from source is similar to building the standard MySQL Server, although it differs in a few key respects discussed here. For general information about building MySQL from source, see Section 2.9, “Installing MySQL from Source”. For information about compiling MySQL Cluster on Windows platforms, see Section 16.2.2.2, “Compiling and Installing MySQL Cluster from Source on Windows”.

Building MySQL Cluster requires using the MySQL Cluster sources. These are available from the MySQL Cluster downloads page at http://dev.mysql.com/downloads/cluster/. The archived source file should have a name similar to mysql-cluster-gpl-7.2.5.tar.gz. You can also obtain MySQL development sources from launchpad.net. Attempting to build MySQL Cluster from standard MySQL Server 5.5 sources is not supported.

The WITH_NDBCLUSTER_STORAGE_ENGINE option for CMake causes the binaries for the management nodes, data nodes, and other MySQL Cluster programs to be built; it also causes mysqld to be compiled with NDB storage engine support. This option is enabled by default in the MySQL Cluster NDB 7.2 sources.

For more information about CMake options specific to building MySQL Cluster, see Options for Compiling MySQL Cluster.

After you have run make && make install (or your system's equivalent), the result is similar to what is obtained by unpacking a precompiled binary to the same location.

Management nodes.  When building from source and running the default make install, the management server and management client binaries (ndb_mgmd and ndb_mgm) can be found in /usr/local/mysql/bin. Only ndb_mgmd is required to be present on a management node host; however, it is also a good idea to have ndb_mgm present on the same host machine. Neither of these executables requires a specific location on the host machine's file system.

Data nodes.  The only executable required on a data node host is the data node binary ndbd or ndbmtd. (mysqld, for example, does not have to be present on the host machine.) By default, when building from source, this file is placed in the directory /usr/local/mysql/bin. For installing on multiple data node hosts, only ndbd or ndbmtd need be copied to the other host machine or machines. (This assumes that all data node hosts use the same architecture and operating system; otherwise you may need to compile separately for each different platform.) The data node binary need not be in any particular location on the host's file system, as long as the location is known.

When compiling MySQL Cluster from source, no special options are required for building multi-threaded data node binaries. Configuring the build with NDB storage engine support causes ndbmtd to be built automatically; make install places the ndbmtd binary in the installation bin directory along with mysqld, ndbd, and ndb_mgm.

SQL nodes.  If you compile MySQL with clustering support, and perform the default installation (using make install as the system root user), mysqld is placed in /usr/local/mysql/bin. Follow the steps given in Section 2.9, “Installing MySQL from Source” to make mysqld ready for use. If you want to run multiple SQL nodes, you can use a copy of the same mysqld executable and its associated support files on several machines. The easiest way to do this is to copy the entire /usr/local/mysql directory and all directories and files contained within it to the other SQL node host or hosts, then repeat the steps from Section 2.9, “Installing MySQL from Source” on each machine. If you configure the build with a nondefault PREFIX option, you must adjust the directory accordingly.

In Section 16.2.3, “Initial Configuration of MySQL Cluster”, we create configuration files for all of the nodes in our example MySQL Cluster.

16.2.2. Installing MySQL Cluster on Windows

MySQL Cluster NDB 7.2 binaries for Windows can be obtained from http://dev.mysql.com/downloads/cluster/. For information about installing MySQL Cluster on Windows from a binary release provided by Oracle, see Section 16.2.2.1, “Installing MySQL Cluster on Windows from a Binary Release”.

It is also possible to compile and install MySQL Cluster from source on Windows using Microsoft Visual Studio. For more information, see Section 16.2.2.2, “Compiling and Installing MySQL Cluster from Source on Windows”.

16.2.2.1. Installing MySQL Cluster on Windows from a Binary Release

This section describes a basic installation of MySQL Cluster on Windows using a binary no-install MySQL Cluster release provided by Oracle, using the same 4-node setup outlined in the beginning of this section (see Section 16.2, “MySQL Cluster Installation”), as shown in the following table:

NodeIP Address
Management (MGMD) node192.168.0.10
MySQL server (SQL) node192.168.0.20
Data (NDBD) node "A"192.168.0.30
Data (NDBD) node "B"192.168.0.40

As on other platforms, the MySQL Cluster host computer running an SQL node must have installed on it a MySQL Server binary (mysqld.exe). You should also have the MySQL client (mysql.exe) on on this host. For management nodes and data nodes, it is not necessary to install the MySQL Server binary; however, each management node requires the management server daemon (ndb_mgmd.exe); each data node requires the data node daemon (ndbd.exe or ndbmtd.exe). For this example, we refer to ndbd.exe as the data node executable, but you can install ndbmtd.exe, the multi-threaded version of this program, instead, in exactly the same way. You should also install the management client (ndb_mgm.exe) on the management server host. This section covers the steps necessary to install the correct Windows binaries for each type of MySQL Cluster node.

Замечание

As with other Windows programs, MySQL Cluster executables are named with the .exe file extension. However, it is not necessary to include the .exe extension when invoking these programs from the command line. Therefore, we often simply refer to these programs in this documentation as mysqld, mysql, ndb_mgmd, and so on. You should understand that, whether we refer (for example) to mysqld or mysqld.exe, either name means the same thing (the MySQL Server program).

For setting up a MySQL Cluster using Oracles's no-install binaries, the first step in the installation process is to download the latest MySQL Cluster Windows binary archive from http://dev.mysql.com/downloads/cluster/. This archive has a filename of the form mysql-cluster-gpl-noinstall-ver-winarch.zip, where ver is the NDB storage engine version (such as 7.2.1), and arch is the architecture (32 for 32-bit binaries, and 64 for 64-bit binaries). For example, the MySQL Cluster NDB 7.2.1 no-install archive for 32-bit Windows systems is named mysql-cluster-gpl-noinstall-7.2.1-win32.zip.

You can run 32-bit MySQL Cluster binaries on both 32-bit and 64-bit versions of Windows; however, 64-bit MySQL Cluster binaries can be used only on 64-bit versions of Windows. If you are using a 32-bit version of Windows on a computer that has a 64-bit CPU, then you must use the 32-bit MySQL Cluster binaries.

To minimize the number of files that need to be downloaded from the Internet or copied between machines, we start with the computer where you intend to run the SQL node.

SQL node.  We assume that you have placed a copy of the no-install archive in the directory C:\Documents and Settings\username\My Documents\Downloads on the computer having the IP address 192.168.0.20, where username is the name of the current user. (You can obtain this name using ECHO %USERNAME% on the command line.) To install and run MySQL Cluster executables as Windows services, this user should be a member of the Administrators group.

Extract all the files from the archive. The Extraction Wizard integrated with Windows Explorer is adequate for this task. (If you use a different archive program, be sure that it extracts all files and directories from the archive, and that it preserves the archive's directory structure.) When you are asked for a destination directory, enter C:\, which causes the Extraction Wizard to extract the archive to the directory C:\mysql-cluster-gpl-noinstall-ver-winarch. Rename this directory to C:\mysql.

It is possible to install the MySQL Cluster binaries to directories other than C:\mysql\bin; however, if you do so, you must modify the paths shown in this procedure accordingly. In particular, if the MySQL Server (SQL node) binary is installed to a location other than C:\mysql or C:\Program Files\MySQL\MySQL Server 5.5, or if the SQL node's data directory is in a location other than C:\mysql\data or C:\Program Files\MySQL\MySQL Server 5.5\data, extra configuration options must be used on the command line or added to the my.ini or my.cnf file when starting the SQL node. For more information about configuring a MySQL Server to run in a nonstandard location, see Section 2.3.6, “Installing MySQL on Microsoft Windows Using a noinstall Zip Archive”.

For a MySQL Server with MySQL Cluster support to run as part of a MySQL Cluster, it must be started with the options --ndbcluster and --ndb-connectstring. While you can specify these options on the command line, it is usually more convenient to place them in an option file. To do this, create a new text file in Notepad or another text editor. Enter the following configuration information into this file:

[mysqld]
# Options for mysqld process:
ndbcluster                      # run NDB storage engine
ndb-connectstring=192.168.0.10  # location of management server

You can add other options used by this MySQL Server if desired (see Section 2.3.6.2, “Creating an Option File”), but the file must contain the options shown, at a minimum. Save this file as C:\mysql\my.ini. This completes the installation and setup for the SQL node.

Data nodes.  A MySQL Cluster data node on a Windows host requires only a single executable, one of either ndbd.exe or ndbmtd.exe. For this example, we assume that you are using ndbd.exe, but the same instructions apply when using ndbmtd.exe. On each computer where you wish to run a data node (the computers having the IP addresses 192.168.0.30 and 192.168.0.40), create the directories C:\mysql, C:\mysql\bin, and C:\mysql\cluster-data; then, on the computer where you downloaded and extracted the no-install archive, locate ndbd.exe in the C:\mysql\bin directory. Copy this file to the C:\mysql\bin directory on each of the two data node hosts.

To function as part of a MySQL Cluster, each data node must be given the address or hostname of the management server. You can supply this information on the command line using the --ndb-connectstring or -c option when starting each data node process. However, it is usually preferable to put this information in an option file. To do this, create a new text file in Notepad or another text editor and enter the following text:

[mysql_cluster]
# Options for data node process:
ndb-connectstring=192.168.0.10  # location of management server

Save this file as C:\mysql\my.ini on the data node host. Create another text file containing the same information and save it on as C:mysql\my.ini on the other data node host, or copy the my.ini file from the first data node host to the second one, making sure to place the copy in the second data node's C:\mysql directory. Both data node hosts are now ready to be used in the MySQL Cluster, which leaves only the management node to be installed and configured.

Management node.  The only executable program required on a computer used for hosting a MySQL Cluster management node is the management server program ndb_mgmd.exe. However, in order to administer the MySQL Cluster once it has been started, you should also install the MySQL Cluster management client program ndb_mgm.exe on the same machine as the management server. Locate these two programs on the machine where you downloaded and extracted the no-install archive; this should be the directory C:\mysql\bin on the SQL node host. Create the directory C:\mysql\bin on the computer having the IP address 192.168.0.10, then copy both programs to this directory.

You should now create two configuration files for use by ndb_mgmd.exe:

  1. A local configuration file to supply configuration data spcific to the management node itself. Typically, this file needs only to supply the location of the MySQL Cluster global configuration file (see item 2).

    To create this file, start a new text file in Notepad or another text editor, and enter the following information:

    [mysql_cluster]
    # Options for management node process
    config-file=C:/mysql/bin/config.ini

    Save this file as the plaintext file C:\mysql\bin\my.ini.

  2. A global configuration file from which the management node can obtain configuration information governing the MySQL Cluster as a whole. At a minimum, this file must contain a section for each node in the MySQL Cluster, and the IP addresses or hostnames for the management node and all data nodes (HostName configuration parameter). It is also advisable to include the following additional information:

    Create a new text file using a text editor such as Notepad, and input the following information:

    [ndbd default]
    # Options affecting ndbd processes on all data nodes:
    NoOfReplicas=2                      # Number of replicas
    DataDir=C:/mysql/bin/cluster-data   # Directory for each data node's data files
                                        # Forward slashes used in directory path,
                                        # rather than backslashes. This is correct;
                                        # see Important note in text
    DataMemory=80M    # Memory allocated to data storage
    IndexMemory=18M   # Memory allocated to index storage
                      # For DataMemory and IndexMemory, we have used the
                      # default values. Since the "world" database takes up
                      # only about 500KB, this should be more than enough for
                      # this example Cluster setup.
    
    [ndb_mgmd]
    # Management process options:
    HostName=192.168.0.10               # Hostname or IP address of management node
    DataDir=C:/mysql/bin/cluster-logs   # Directory for management node log files
    
    [ndbd]
    # Options for data node "A":
                                    # (one [ndbd] section per data node)
    HostName=192.168.0.30           # Hostname or IP address
    
    [ndbd]
    # Options for data node "B":
    HostName=192.168.0.40           # Hostname or IP address
    
    [mysqld]
    # SQL node options:
    HostName=192.168.0.20           # Hostname or IP address
    

    Save this file as the plaintext file C:\mysql\bin\config.ini.

Important

A single backslash character (\) cannot be used when specifying directory paths in program options or configuration files used by MySQL Cluster on Windows. Instead, you must either escape each backslash character with a second backslash (\\), or replace the backslash with a forward slash character (/). For example, the following line from the [ndb_mgmd] section of a MySQL Cluster config.ini file does not work:

DataDir=C:\mysql\bin\cluster-logs

Instead, you may use either of the following:

DataDir=C:\\mysql\\bin\\cluster-logs  # Escaped backslashes
DataDir=C:/mysql/bin/cluster-logs     # Forward slashes

For reasons of brevity and legibility, we recommend that you use forward slashes in directory paths used in MySQL Cluster program options and configuration files on Windows.

16.2.2.2. Compiling and Installing MySQL Cluster from Source on Windows

Oracle provides precompiled MySQL Cluster binaries for Windows which should be adequate for most users. However, if you wish, it is also possible to compile MySQL Cluster for Windows from source code. The procedure for doing this is almost identical to the procedure used to compile the standard MySQL Server binaries for Windows, and uses the same tools. However, there are two major differences:

  • To build MySQL Cluster, you must use the MySQL Cluster sources, which you can obtain from http://dev.mysql.com/downloads/cluster/.

    Attempting to build MySQL Cluster from the source code for the standard MySQL Server is likely not to be successful, and is not supported by Oracle.

  • You must configure the build using the WITH_NDBCLUSTER_STORAGE_ENGINE option in addition to any other build options you wish to use before creating the Visual Studio project files. Once you have run configure.js with the desired options, you can create the project files and build from them in the same manner as you do when compiling the standard MySQL Server. For more information, see Installing MySQL from Source on Windows.

Once the build process is complete, you can create a Zip archive containing the compiled binaries by executing make package. The MySQL Cluster binaries can be found in the bin directory of the resulting archive, which is equivalent to the no-install archive, and which can be installed and configured in the same manner. For more information, see Section 16.2.2.1, “Installing MySQL Cluster on Windows from a Binary Release”.

16.2.2.3. Initial Startup of MySQL Cluster on Windows

Once the MySQL Cluster executables and needed configuration files are in place, performing an initial start of the cluster is simply a matter of starting the MySQL Cluster executables for all nodes in the cluster. Each cluster node process must be started separately, and on the host computer where it resides. The management node should be started first, followed by the data nodes, and then finally by any SQL nodes.

  1. On the management node host, issue the following command from the command line to start the management node process:

    C:\mysql\bin> ndb_mgmd
    2010-06-23 07:53:34 [MgmtSrvr] INFO     -- NDB Cluster Management Server. mysql-5.1.61-ndb-7.1.20
    2010-06-23 07:53:34 [MgmtSrvr] INFO     -- Reading cluster configuration from 'config.ini'
    

    The management node process continues to print logging output to the console. This is normal, because the management node is not running as a Windows service. (If you have used MySQL Cluster on a Unix-like platform such as Linux, you may notice that the management node's default behavior in this regard on Windows is effectively the opposite of its behavior on Unix systems, where it runs by default as a Unix daemon process. This behavior is also true of MySQL Cluster data node processes running on Windows.) For this reason, do not close the window in which ndb_mgmd.exe is running; doing so kills the management node process. (See Section 16.2.2.4, “Installing MySQL Cluster Processes as Windows Services”, where we show how to install and run MySQL Cluster processes as Windows services.)

    The required -f option tells the management node where to find the global configuration file (config.ini). The long form of this option is --config-file.

    Important

    A MySQL Cluster management node caches the configuration data that it reads from config.ini; once it has created a configuration cache, it ignores the config.ini file on subsequent starts unless forced to do otherwise. This means that, if the management node fails to start due to an error in this file, you must make the management node re-read config.ini after you have corrected any errors in it. You can do this by starting ndb_mgmd.exe with the --reload or --initial option on the command line. Either of these options works to refresh the configuration cache.

    It is not necessary or advisable to use either of these options in the management node's my.ini file.

    For additional information about options which can be used with ndb_mgmd, see Section 16.4.4, “ndb_mgmd — The MySQL Cluster Management Server Daemon”, as well as Section 16.4.23, “Options Common to MySQL Cluster Programs”.

  2. On each of the data node hosts, run the command shown here to start the data node processes:

    C:\mysql\bin> ndbd
    2010-06-23 07:53:46 [ndbd] INFO     -- Configuration fetched from 'localhost:1186', generation: 1
    

    In each case, the first line of output from the data node process should resemble what is shown in the preceding example, and is followed by additional lines of logging output. As with the management node process, this is normal, because the data node is not running as a Windows service. For this reason, do not close the console window in which the data node process is running; doing so kills ndbd.exe. (For more information, see Section 16.2.2.4, “Installing MySQL Cluster Processes as Windows Services”.)

  3. Do not start the SQL node yet; it cannot connect to the cluster until the data nodes have finished starting, which may take some time. Instead, in a new console window on the management node host, start the MySQL Cluster management client ndb_mgm.exe, which should be in C:\mysql\bin on the management node host. (Do not try to re-use the console window where ndb_mgmd.exe is running by typing CTRL+C, as this kills the management node.) The resulting output should look like this:

    C:\mysql\bin> ndb_mgm
    -- NDB Cluster -- Management Client --
    ndb_mgm>
    

    When the prompt ndb_mgm> appears, this indicates that the management client is ready to receive MySQL Cluster management commands. You can observe the status of the data nodes as they start by entering ALL STATUS at the management client prompt. This command causes a running report of the data nodes's startup sequence, which should look something like this:

    ndb_mgm> ALL STATUS
    Connected to Management Server at: localhost:1186
    Node 2: starting (Last completed phase 3) (mysql-5.1.61-ndb-7.1.20)
    Node 3: starting (Last completed phase 3) (mysql-5.1.61-ndb-7.1.20)
    
    Node 2: starting (Last completed phase 4) (mysql-5.1.61-ndb-7.1.20)
    Node 3: starting (Last completed phase 4) (mysql-5.1.61-ndb-7.1.20)
    
    Node 2: Started (version 7.1.20)
    Node 3: Started (version 7.1.20)
    
    ndb_mgm>
    
    Замечание

    Commands issued in the management client are not case-sensitive; we use uppercase as the canonical form of these commands, but you are not required to observe this convention when inputting them into the ndb_mgm client. For more information, see Section 16.5.2, “Commands in the MySQL Cluster Management Client”.

    The output produced by ALL STATUS is likely to vary from what is shown here, according to the speed at which the data nodes are able to start, the release version number of the MySQL Cluster software you are using, and other factors. What is significant is that, when you see that both data nodes have started, you are ready to start the SQL node.

    You can leave ndb_mgm.exe running; it has no negative impact on the performance of the MySQL Cluster, and we use it in the next step to verify that the SQL node is connected to the cluster after you have started it.

  4. On the computer designated as the SQL node host, open a console window and navigate to the directory where you unpacked the MySQL Cluster binaries (if you are following our example, this is C:\mysql\bin).

    Start the SQL node by invoking mysqld.exe from the command line, as shown here:

    C:\mysql\bin> mysqld --console
    

    The --console option causes logging information to be written to the console, which can be helpful in the event of problems. (Once you are satisfied that the SQL node is running in a satisfactory manner, you can stop it and restart it out without the --console option, so that logging is performed normally.)

    In the console window where the management client (ndb_mgm.exe) is running on the management node host, enter the SHOW command, which should produce output similar to what is shown here:

    ndb_mgm> SHOW
    Connected to Management Server at: localhost:1186
    Cluster Configuration
    ---------------------
    [ndbd(NDB)]     2 node(s)
    id=2    @192.168.0.30  (Version: 5.1.61-ndb-7.1.20, Nodegroup: 0, Master)
    id=3    @192.168.0.40  (Version: 5.1.61-ndb-7.1.20, Nodegroup: 0)
    
    [ndb_mgmd(MGM)] 1 node(s)
    id=1    @192.168.0.10  (Version: 5.1.61-ndb-7.1.20)
    
    [mysqld(API)]   1 node(s)
    id=4    @192.168.0.20  (Version: 5.1.61-ndb-7.1.20)
    

    You can also verify that the SQL node is connected to the MySQL Cluster in the mysql client (mysql.exe) using the SHOW ENGINE NDB STATUS statement.

You should now be ready to work with database objects and data using MySQL Cluster's NDBCLUSTER storage engine. See Section 16.2.5, “MySQL Cluster Пример with Tables and Data”, for more information and examples.

You can also install ndb_mgmd.exe, ndbd.exe, and ndbmtd.exe as Windows services. For information on how to do this, see Section 16.2.2.4, “Installing MySQL Cluster Processes as Windows Services”).

16.2.2.4. Installing MySQL Cluster Processes as Windows Services

Once you are satisfied that MySQL Cluster is running as desired, you can install the management nodes and data nodes as Windows services, so that these processes are started and stopped automatically whenever Windows is started or stopped. This also makes it possible to control these processes from the command line with the appropriate NET START or NET STOP command, or using the Windows graphical Services utility.

Installing programs as Windows services usually must be done using an account that has Administrator rights on the system.

To install the management node as a service on Windows, invoke ndb_mgmd.exe from the command line on the machine hosting the management node, using the --install option, as shown here:

C:\> C:\mysql\bin\ndb_mgmd.exe --install
Installing service 'MySQL Cluster Management Server' as '"C:\mysql\bin\ndbd.exe" "--service=ndb_mgmd"'
Service successfully installed.
Important

When installing a MySQL Cluster program as a Windows service, you should always specify the complete path; otherwise the service installation may fail with the error The system cannot find the file specified.

The --install option must be used first, ahead of any other options that might be specified for ndb_mgmd.exe. However, it is preferable to specify such options in an options file instead. If your options file is not in one of the default locations as shown in the output of ndb_mgmd.exe --help, you can specify the location using the --config-file option.

Now you should be able to start and stop the management server like this:

C:\> NET START ndb_mgmd
The MySQL Cluster Management Server service is starting.
The MySQL Cluster Management Server service was started successfully.

C:\> NET STOP ndb_mgmd
The MySQL Cluster Management Server service is stopping..
The MySQL Cluster Management Server service was stopped successfully.

You can also start or stop the management server as a Windows service using the descriptive name, as shown here:

C:\> NET START 'MySQL Cluster Management Server'
The MySQL Cluster Management Server service is starting.
The MySQL Cluster Management Server service was started successfully.

C:\> NET STOP  'MySQL Cluster Management Server'
The MySQL Cluster Management Server service is stopping..
The MySQL Cluster Management Server service was stopped successfully.

However, it is usually simpler to specify a short service name or to permit the default service name to be used when installing the service, and then reference that name when starting or stopping the service. To specify a service name other than ndb_mgmd, append it to the --install option, as shown in this example:

C:\> C:\mysql\bin\ndb_mgmd.exe --install=mgmd1
Installing service 'MySQL Cluster Management Server' as '"C:\mysql\bin\ndb_mgmd.exe" "--service=mgmd1"'
Service successfully installed.

Now you should be able to start or stop the service using the name you have specified, like this:

C:\> NET START mgmd1
The MySQL Cluster Management Server service is starting.
The MySQL Cluster Management Server service was started successfully.

C:\> NET STOP mgmd1
The MySQL Cluster Management Server service is stopping..
The MySQL Cluster Management Server service was stopped successfully.

To remove the management node service, invoke ndb_mgmd.exe with the --remove option, as shown here:

C:\> C:\mysql\bin\ndb_mgmd.exe --remove
Removing service 'MySQL Cluster Management Server'
Service successfully removed.

If you installed the service using a service name other than the default, you can remove the service by passing this name as the value of the --remove option, like this:

C:\> C:\mysql\bin\ndb_mgmd.exe --remove=mgmd1
Removing service 'mgmd1'
Service successfully removed.

Installation of a MySQL Cluster data node processs as a Windows service can be done in a similar fashion, using the --install option for ndbd.exe (or ndbmtd.exe), as shown here:

C:\> C:\mysql\bin\ndbd.exe --install
Installing service 'MySQL Cluster Data Node Daemon' as '"C:\mysql\bin\ndbd.exe" "--service=ndbd"'
Service successfully installed.

Now you can start or stop the data node using either the default service name or the descriptive name with net start or net stop, as shown in the following example:

C:\> NET START ndbd
The MySQL Cluster Data Node Daemon service is starting.
The MySQL Cluster Data Node Daemon service was started successfully.

C:\> NET STOP ndbd
The MySQL Cluster Data Node Daemon service is stopping..
The MySQL Cluster Data Node Daemon service was stopped successfully.

C:\> NET START 'MySQL Cluster Data Node Daemon'
The MySQL Cluster Data Node Daemon service is starting.
The MySQL Cluster Data Node Daemon service was started successfully.

C:\> NET STOP 'MySQL Cluster Data Node Daemon'
The MySQL Cluster Data Node Daemon service is stopping..
The MySQL Cluster Data Node Daemon service was stopped successfully.

To remove the data node service, invoke ndbd.exe with the --remove option, as shown here:

C:\> C:\mysql\bin\ndbd.exe --remove
Removing service 'MySQL Cluster Data Node Daemon'
Service successfully removed.

As with ndb_mgmd.exe (and mysqld.exe), when installing ndbd.exe as a Windows service, you can also specify a name for the service as the value of --install, and then use it when starting or stopping the service, like this:

C:\> C:\mysql\bin\ndbd.exe --install=dnode1
Installing service 'dnode1' as '"C:\mysql\bin\ndbd.exe" "--service=dnode1"'
Service successfully installed.

C:\> NET START dnode1
The MySQL Cluster Data Node Daemon service is starting.
The MySQL Cluster Data Node Daemon service was started successfully.

C:\> NET STOP dnode1
The MySQL Cluster Data Node Daemon service is stopping..
The MySQL Cluster Data Node Daemon service was stopped successfully.

If you specified a service name when installing the data node service, you can use this name when removing it as well, by passing it as the value of the --remove option, as shown here:

C:\> C:\mysql\bin\ndbd.exe --remove=dnode1
Removing service 'dnode1'
Service successfully removed.

Installation of the SQL node as a Windows service, starting the service, stopping the service, and removing the service are done in a similar fashion, using mysqld --install, NET START, NET STOP, and mysqld --remove. For additional information, see Section 2.3.6.7, “Starting MySQL as a Windows Service”.

16.2.3. Initial Configuration of MySQL Cluster

For our four-node, four-host MySQL Cluster, it is necessary to write four configuration files, one per node host.

  • Each data node or SQL node requires a my.cnf file that provides two pieces of information: a connectstring that tells the node where to find the management node, and a line telling the MySQL server on this host (the machine hosting the data node) to enable the NDBCLUSTER storage engine.

    For more information on connectstrings, see Section 16.3.2.3, “The MySQL Cluster Connectstring”.

  • The management node needs a config.ini file telling it how many replicas to maintain, how much memory to allocate for data and indexes on each data node, where to find the data nodes, where to save data to disk on each data node, and where to find any SQL nodes.

Configuring the data nodes and SQL nodes.  The my.cnf file needed for the data nodes is fairly simple. The configuration file should be located in the /etc directory and can be edited using any text editor. (Create the file if it does not exist.) For example:

shell> vi /etc/my.cnf
Замечание

We show vi being used here to create the file, but any text editor should work just as well.

For each data node and SQL node in our example setup, my.cnf should look like this:

[mysqld]
# Options for mysqld process:
ndbcluster                      # run NDB storage engine
ndb-connectstring=192.168.0.10  # location of management server

[mysql_cluster]
# Options for ndbd process:
ndb-connectstring=192.168.0.10  # location of management server

After entering the preceding information, save this file and exit the text editor. Do this for the machines hosting data node “A”, data node “B”, and the SQL node.

Important

Once you have started a mysqld process with the NDBCLUSTER and ndb-connectstring parameters in the [mysqld] in the my.cnf file as shown previously, you cannot execute any CREATE TABLE or ALTER TABLE statements without having actually started the cluster. Otherwise, these statements will fail with an error. This is by design.

Configuring the management node.  The first step in configuring the management node is to create the directory in which the configuration file can be found and then to create the file itself. For example (running as root):

shell> mkdir /var/lib/mysql-cluster
shell> cd /var/lib/mysql-cluster
shell> vi config.ini

For our representative setup, the config.ini file should read as follows:

[ndbd default]
# Options affecting ndbd processes on all data nodes:
NoOfReplicas=2    # Number of replicas
DataMemory=80M    # How much memory to allocate for data storage
IndexMemory=18M   # How much memory to allocate for index storage
                  # For DataMemory and IndexMemory, we have used the
                  # default values. Since the "world" database takes up
                  # only about 500KB, this should be more than enough for
                  # this example Cluster setup.

[tcp default]
# TCP/IP options:
portnumber=2202   # This the default; however, you can use any
                  # port that is free for all the hosts in the cluster
                  # Note: It is recommended that you do not specify the port
                  # number at all and simply allow the default value to be used
                  # instead

[ndb_mgmd]
# Management process options:
hostname=192.168.0.10           # Hostname or IP address of MGM node
datadir=/var/lib/mysql-cluster  # Directory for MGM node log files

[ndbd]
# Options for data node "A":
                                # (one [ndbd] section per data node)
hostname=192.168.0.30           # Hostname or IP address
datadir=/usr/local/mysql/data   # Directory for this data node's data files

[ndbd]
# Options for data node "B":
hostname=192.168.0.40           # Hostname or IP address
datadir=/usr/local/mysql/data   # Directory for this data node's data files

[mysqld]
# SQL node options:
hostname=192.168.0.20           # Hostname or IP address
                                # (additional mysqld connections can be
                                # specified for this node for various
                                # purposes such as running ndb_restore)
Замечание

The world database can be downloaded from http://dev.mysql.com/doc/, where it can be found listed under “Examples”.

After all the configuration files have been created and these minimal options have been specified, you are ready to proceed with starting the cluster and verifying that all processes are running. We discuss how this is done in Section 16.2.4, “Initial Startup of MySQL Cluster”.

For more detailed information about the available MySQL Cluster configuration parameters and their uses, see Section 16.3.2, “MySQL Cluster Configuration Files”, and Section 16.3, “MySQL Cluster Configuration”. For configuration of MySQL Cluster as relates to making backups, see Section 16.5.3.3, “Configuration for MySQL Cluster Backups”.

Замечание

The default port for Cluster management nodes is 1186; the default port for data nodes is 2202. However, the cluster can automatically allocate ports for data nodes from those that are already free.

16.2.4. Initial Startup of MySQL Cluster

Starting the cluster is not very difficult after it has been configured. Each cluster node process must be started separately, and on the host where it resides. The management node should be started first, followed by the data nodes, and then finally by any SQL nodes:

  1. On the management host, issue the following command from the system shell to start the management node process:

    shell> ndb_mgmd -f /var/lib/mysql-cluster/config.ini
    

    The frist time that it is started, ndb_mgmd must be told where to find its configuration file, using the -f or --config-file option. (See Section 16.4.4, “ndb_mgmd — The MySQL Cluster Management Server Daemon”, for details.)

    For additional options which can be used with ndb_mgmd, see Section 16.4.23, “Options Common to MySQL Cluster Programs”.

  2. On each of the data node hosts, run this command to start the ndbd process:

    shell> ndbd
    
  3. If you used RPM files to install MySQL on the cluster host where the SQL node is to reside, you can (and should) use the supplied startup script to start the MySQL server process on the SQL node.

If all has gone well, and the cluster has been set up correctly, the cluster should now be operational. You can test this by invoking the ndb_mgm management node client. The output should look like that shown here, although you might see some slight differences in the output depending upon the exact version of MySQL that you are using:

shell> ndb_mgm
-- NDB Cluster -- Management Client --
ndb_mgm> SHOW
Connected to Management Server at: localhost:1186
Cluster Configuration
---------------------
[ndbd(NDB)]     2 node(s)
id=2    @192.168.0.30  (Version: 5.5.20-ndb-7.2.5, Nodegroup: 0, Master)
id=3    @192.168.0.40  (Version: 5.5.20-ndb-7.2.5, Nodegroup: 0)

[ndb_mgmd(MGM)] 1 node(s)
id=1    @192.168.0.10  (Version: 5.5.20-ndb-7.2.5)

[mysqld(API)]   1 node(s)
id=4    @192.168.0.20  (Version: 5.5.20-ndb-7.2.5)

The SQL node is referenced here as [mysqld(API)], which reflects the fact that the mysqld process is acting as a MySQL Cluster API node.

Замечание

The IP address shown for a given MySQL Cluster SQL or other API node in the output of SHOW is the address used by the SQL or API node to connect to the cluster data nodes, and not to any management node.

You should now be ready to work with databases, tables, and data in MySQL Cluster. See Section 16.2.5, “MySQL Cluster Пример with Tables and Data”, for a brief discussion.

16.2.5. MySQL Cluster Пример with Tables and Data

Замечание

The information in this section applies to MySQL Cluster running on both Unix and Windows platforms.

Working with database tables and data in MySQL Cluster is not much different from doing so in standard MySQL. There are two key points to keep in mind:

  • For a table to be replicated in the cluster, it must use the NDBCLUSTER storage engine. To specify this, use the ENGINE=NDBCLUSTER or ENGINE=NDB option when creating the table:

    CREATE TABLE tbl_name (col_name column_definitions) ENGINE=NDBCLUSTER;
    

    Alternatively, for an existing table that uses a different storage engine, use ALTER TABLE to change the table to use NDBCLUSTER:

    ALTER TABLE tbl_name ENGINE=NDBCLUSTER;
    
  • Every NDBCLUSTER table has a primary key. If no primary key is defined by the user when a table is created, the NDBCLUSTER storage engine automatically generates a hidden one. Such a key takes up space just as does any other table index. (It is not uncommon to encounter problems due to insufficient memory for accommodating these automatically created indexes.)

If you are importing tables from an existing database using the output of mysqldump, you can open the SQL script in a text editor and add the ENGINE option to any table creation statements, or replace any existing ENGINE options. Suppose that you have the world sample database on another MySQL server that does not support MySQL Cluster, and you want to export the City table:

shell> mysqldump --add-drop-table world City > city_table.sql

The resulting city_table.sql file will contain this table creation statement (and the INSERT statements necessary to import the table data):

DROP TABLE IF EXISTS `City`;
CREATE TABLE `City` (
  `ID` int(11) NOT NULL auto_increment,
  `Name` char(35) NOT NULL default '',
  `CountryCode` char(3) NOT NULL default '',
  `District` char(20) NOT NULL default '',
  `Population` int(11) NOT NULL default '0',
  PRIMARY KEY  (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

INSERT INTO `City` VALUES (1,'Kabul','AFG','Kabol',1780000);
INSERT INTO `City` VALUES (2,'Qandahar','AFG','Qandahar',237500);
INSERT INTO `City` VALUES (3,'Herat','AFG','Herat',186800);(remaining INSERT statements omitted)

You need to make sure that MySQL uses the NDBCLUSTER storage engine for this table. There are two ways that this can be accomplished. One of these is to modify the table definition before importing it into the Cluster database. Using the City table as an example, modify the ENGINE option of the definition as follows:

DROP TABLE IF EXISTS `City`;
CREATE TABLE `City` (
  `ID` int(11) NOT NULL auto_increment,
  `Name` char(35) NOT NULL default '',
  `CountryCode` char(3) NOT NULL default '',
  `District` char(20) NOT NULL default '',
  `Population` int(11) NOT NULL default '0',
  PRIMARY KEY  (`ID`)
) ENGINE=NDBCLUSTER DEFAULT CHARSET=latin1;

INSERT INTO `City` VALUES (1,'Kabul','AFG','Kabol',1780000);
INSERT INTO `City` VALUES (2,'Qandahar','AFG','Qandahar',237500);
INSERT INTO `City` VALUES (3,'Herat','AFG','Herat',186800);
(remaining INSERT statements omitted)

This must be done for the definition of each table that is to be part of the clustered database. The easiest way to accomplish this is to do a search-and-replace on the file that contains the definitions and replace all instances of TYPE=engine_name or ENGINE=engine_name with ENGINE=NDBCLUSTER. If you do not want to modify the file, you can use the unmodified file to create the tables, and then use ALTER TABLE to change their storage engine. The particulars are given later in this section.

Assuming that you have already created a database named world on the SQL node of the cluster, you can then use the mysql command-line client to read city_table.sql, and create and populate the corresponding table in the usual manner:

shell> mysql world < city_table.sql

It is very important to keep in mind that the preceding command must be executed on the host where the SQL node is running (in this case, on the machine with the IP address 192.168.0.20).

To create a copy of the entire world database on the SQL node, use mysqldump on the noncluster server to export the database to a file named world.sql; for example, in the /tmp directory. Then modify the table definitions as just described and import the file into the SQL node of the cluster like this:

shell> mysql world < /tmp/world.sql

If you save the file to a different location, adjust the preceding instructions accordingly.

Running SELECT queries on the SQL node is no different from running them on any other instance of a MySQL server. To run queries from the command line, you first need to log in to the MySQL Monitor in the usual way (specify the root password at the Enter password: prompt):

shell> mysql -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 5.5.20-ndb-7.2.5

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

We simply use the MySQL server's root account and assume that you have followed the standard security precautions for installing a MySQL server, including setting a strong root password. For more information, see Section 2.10.2, “Securing the Initial MySQL Accounts”.

It is worth taking into account that Cluster nodes do not make use of the MySQL privilege system when accessing one another. Setting or changing MySQL user accounts (including the root account) effects only applications that access the SQL node, not interaction between nodes. See Section 16.5.10.2, “MySQL Cluster and MySQL Privileges”, for more information.

If you did not modify the ENGINE clauses in the table definitions prior to importing the SQL script, you should run the following statements at this point:

mysql> USE world;
mysql> ALTER TABLE City ENGINE=NDBCLUSTER;
mysql> ALTER TABLE Country ENGINE=NDBCLUSTER;
mysql> ALTER TABLE CountryLanguage ENGINE=NDBCLUSTER;

Selecting a database and running a SELECT query against a table in that database is also accomplished in the usual manner, as is exiting the MySQL Monitor:

mysql> USE world;
mysql> SELECT Name, Population FROM City ORDER BY Population DESC LIMIT 5;
+-----------+------------+
| Name      | Population |
+-----------+------------+
| Bombay    |   10500000 |
| Seoul     |    9981619 |
| São Paulo |    9968485 |
| Shanghai  |    9696300 |
| Jakarta   |    9604900 |
+-----------+------------+
5 rows in set (0.34 sec)

mysql> \q
Bye

shell>

Applications that use MySQL can employ standard APIs to access NDB tables. It is important to remember that your application must access the SQL node, and not the management or data nodes. This brief example shows how we might execute the SELECT statement just shown by using the PHP 5.X mysqli extension running on a Web server elsewhere on the network:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
  "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
  <meta http-equiv="Content-Type"
           content="text/html; charset=iso-8859-1">
  <title>SIMPLE mysqli SELECT</title>
</head>
<body>
<?php
  # connect to SQL node:
  $link = new mysqli('192.168.0.20', 'root', 'root_password', 'world');
  # parameters for mysqli constructor are:
  #   host, user, password, database

  if( mysqli_connect_errno() )
    die("Connect failed: " . mysqli_connect_error());

  $query = "SELECT Name, Population
            FROM City
            ORDER BY Population DESC
            LIMIT 5";

  # if no errors...
  if( $result = $link->query($query) )
  {
?>
<table border="1" width="40%" cellpadding="4" cellspacing ="1">
  <tbody>
  <tr>
    <th width="10%">City</th>
    <th>Population</th>
  </tr>
<?
    # then display the results...
    while($row = $result->fetch_object())
      printf("<tr>\n  <td align=\"center\">%s</td><td>%d</td>\n</tr>\n",
              $row->Name, $row->Population);
?>
  </tbody
</table>
<?
  # ...and verify the number of rows that were retrieved
    printf("<p>Affected rows: %d</p>\n", $link->affected_rows);
  }
  else
    # otherwise, tell us what went wrong
    echo mysqli_error();

  # free the result set and the mysqli connection object
  $result->close();
  $link->close();
?>
</body>
</html>

We assume that the process running on the Web server can reach the IP address of the SQL node.

In a similar fashion, you can use the MySQL C API, Perl-DBI, Python-mysql, or MySQL Connectors to perform the tasks of data definition and manipulation just as you would normally with MySQL.

16.2.6. Safe Shutdown and Restart of MySQL Cluster

To shut down the cluster, enter the following command in a shell on the machine hosting the management node:

shell> ndb_mgm -e shutdown

The -e option here is used to pass a command to the ndb_mgm client from the shell. (See Section 16.4.23, “Options Common to MySQL Cluster Programs”, for more information about this option.) The command causes the ndb_mgm, ndb_mgmd, and any ndbd or ndbmtd processes to terminate gracefully. Any SQL nodes can be terminated using mysqladmin shutdown and other means. On Windows platforms, assuming that you have installed the SQL node as a Windows service, you can use NET STOP MYSQL.

To restart the cluster on Unix platforms, run these commands:

  • On the management host (192.168.0.10 in our example setup):

    shell> ndb_mgmd -f /var/lib/mysql-cluster/config.ini
    
  • On each of the data node hosts (192.168.0.30 and 192.168.0.40):

    shell> ndbd
    
  • Use the ndb_mgm client to verify that both data nodes have started successfully.

  • On the SQL host (192.168.0.20):

    shell> mysqld_safe &
    

On Windows platforms, assuming that you have installed all MySQL Cluster processes as Windows services using the default service names (see Section 16.2.2.4, “Installing MySQL Cluster Processes as Windows Services”), you can restart the cluster as follows:

  • On the management host (192.168.0.10 in our example setup), execute the following command:

    C:\> NET START ndb_mgmd
    
  • On each of the data node hosts (192.168.0.30 and 192.168.0.40), execute the following command:

    C:\> NET START ndbd
    
  • On the management node host, use the ndb_mgm client to verify that the management node and both data nodes have started successfully (see Section 16.2.2.3, “Initial Startup of MySQL Cluster on Windows”).

  • On the SQL node host (192.168.0.20), execute the following command:

    C:\> NET START mysql
    

In a production setting, it is usually not desirable to shut down the cluster completely. In many cases, even when making configuration changes, or performing upgrades to the cluster hardware or software (or both), which require shutting down individual host machines, it is possible to do so without shutting down the cluster as a whole by performing a rolling restart of the cluster. For more information about doing this, see Section 16.5.4, “Performing a Rolling Restart of a MySQL Cluster”.

16.2.7. Upgrading and Downgrading MySQL Cluster NDB 7.2

This section provides information about MySQL Cluster software and table file compatibility between different MySQL Cluster NDB 7.2 releases with regard to performing upgrades and downgrades as well as compatibility matrices and notes. You are expected already to be familiar with installing and configuring a MySQL Cluster prior to attempting an upgrade or downgrade. See Section 16.3, “MySQL Cluster Configuration”.

Important

Only compatibility between MySQL versions with regard to NDBCLUSTER is taken into account in this section, and there are likely other issues to be considered. As with any other MySQL software upgrade or downgrade, you are strongly encouraged to review the relevant portions of the MySQL Manual for the MySQL versions from which and to which you intend to migrate, before attempting an upgrade or downgrade of the MySQL Cluster software. This is especially true when planning a migration from MySQL Cluster NDB 7.1 (or earlier) to MySQL Cluster NDB 7.2, since the version of the underlying MySQL Server also changes from MySQL 5.1 to MySQL 5.5. See Section 2.11.1, “Upgrading MySQL”.

Versions supported.  The following versions of MySQL Cluster are supported for upgrades to MySQL Cluster NDB 7.2 (7.2.4 and later):

  • MySQL Cluster NDB 7.1 GA releases (7.1.3 and later)

  • MySQL Cluster NDB 7.0 GA releases (7.0.5 and later)

  • MySQL Cluster NDB 6.3 GA releases (6.3.8 and later) that can be upgraded to MySQL Cluster NDB 7.1

For information about upgrades and downgrades in previous MySQL Cluster release series, see Upgrade and Downgrade Compatibility: MySQL Cluster NDB 6.x, and Upgrade and downgrade compatibility: MySQL Cluster NDB 7.x.

NDB API, ClusterJ, and other appplications used with recent releases of MySQL Cluster NDB 6.3 and later should continue to work with MySQL Cluster NDB 7.2.4 and later without rewriting or recompiling.

Upgrading ndbd to ndbmtd When upgrading online from a MySQL Cluster NDB 6.3 release to a MySQL Cluster NDB 7.0 or later release, you should not try to upgrade the data nodes from ndbd to ndbmtd at the same time. Instead, perform the upgrade using the new ndbd executable (from the MySQL Cluster distribution to which you are upgrading) to replace the one in use on the data nodes. Once the version upgrade is complete, you can perform a second (online) upgrade to replace the data node executables with ndbmtd from the “new” MySQL Cluster distribution.

16.3. MySQL Cluster Configuration

A MySQL server that is part of a MySQL Cluster differs in one chief respect from a normal (nonclustered) MySQL server, in that it employs the NDBCLUSTER storage engine. This engine is also referred to simply as NDB, and the two forms of the name are synonymous.

To avoid unnecessary allocation of resources, the server is configured by default with the NDB storage engine disabled. To enable NDB, you must modify the server's my.cnf configuration file, or start the server with the --ndbcluster option.

For more information about --ndbcluster and other MySQL server options specific to MySQL Cluster, see Section 16.3.4.2, “MySQL Server Options for MySQL Cluster”.

The MySQL server is a part of the cluster, so it also must know how to access an MGM node to obtain the cluster configuration data. The default behavior is to look for the MGM node on localhost. However, should you need to specify that its location is elsewhere, this can be done in my.cnf or on the MySQL server command line. Before the NDB storage engine can be used, at least one MGM node must be operational, as well as any desired data nodes.

NDB, the MySQL Cluster storage engine, is available in binary distributions for Linux, Mac OS X, Solaris. and Windows. We are working to support MySQL Cluster on all operating systems supported by the MySQL Server. For information about installing MySQL Cluster, see Section 16.2, “MySQL Cluster Installation”.

16.3.1. Quick Test Setup of MySQL Cluster

To familiarize you with the basics, we will describe the simplest possible configuration for a functional MySQL Cluster. After this, you should be able to design your desired setup from the information provided in the other relevant sections of this chapter.

First, you need to create a configuration directory such as /var/lib/mysql-cluster, by executing the following command as the system root user:

shell> mkdir /var/lib/mysql-cluster

In this directory, create a file named config.ini that contains the following information. Substitute appropriate values for HostName and DataDir as necessary for your system.

# file "config.ini" - showing minimal setup consisting of 1 data node,
# 1 management server, and 3 MySQL servers.
# The empty default sections are not required, and are shown only for
# the sake of completeness.
# Data nodes must provide a hostname but MySQL Servers are not required
# to do so.
# If you don't know the hostname for your machine, use localhost.
# The DataDir parameter also has a default value, but it is recommended to
# set it explicitly.
# Note: [db], [api], and [mgm] are aliases for [ndbd], [mysqld], and [ndb_mgmd],
# respectively. [db] is deprecated and should not be used in new installations.

[ndbd default]
NoOfReplicas= 1

[mysqld  default]
[ndb_mgmd default]
[tcp default]

[ndb_mgmd]
HostName= myhost.example.com

[ndbd]
HostName= myhost.example.com
DataDir= /var/lib/mysql-cluster

[mysqld]
[mysqld]
[mysqld]

You can now start the ndb_mgmd management server. By default, it attempts to read the config.ini file in its current working directory, so change location into the directory where the file is located and then invoke ndb_mgmd:

shell> cd /var/lib/mysql-cluster
shell> ndb_mgmd

Then start a single data node by running ndbd:

shell> ndbd

For command-line options which can be used when starting ndbd, see Section 16.4.23, “Options Common to MySQL Cluster Programs”.

By default, ndbd looks for the management server at localhost on port 1186.

Замечание

If you have installed MySQL from a binary tarball, you will need to specify the path of the ndb_mgmd and ndbd servers explicitly. (Normally, these will be found in /usr/local/mysql/bin.)

Finally, change location to the MySQL data directory (usually /var/lib/mysql or /usr/local/mysql/data), and make sure that the my.cnf file contains the option necessary to enable the NDB storage engine:

[mysqld]
ndbcluster

You can now start the MySQL server as usual:

shell> mysqld_safe --user=mysql &

Wait a moment to make sure the MySQL server is running properly. If you see the notice mysql ended, check the server's .err file to find out what went wrong.

If all has gone well so far, you now can start using the cluster. Connect to the server and verify that the NDBCLUSTER storage engine is enabled:

shell> mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1 to server version: 5.5.22

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SHOW ENGINES\G
...
*************************** 12. row ***************************
Engine: NDBCLUSTER
Support: YES
Comment: Clustered, fault-tolerant, memory-based tables
*************************** 13. row ***************************
Engine: NDB
Support: YES
Comment: Alias for NDBCLUSTER
...

The row numbers shown in the preceding example output may be different from those shown on your system, depending upon how your server is configured.

Try to create an NDBCLUSTER table:

shell> mysql
mysql> USE test;
Database changed

mysql> CREATE TABLE ctest (i INT) ENGINE=NDBCLUSTER;
Query OK, 0 rows affected (0.09 sec)

mysql> SHOW CREATE TABLE ctest \G
*************************** 1. row ***************************
       Table: ctest
Create Table: CREATE TABLE `ctest` (
  `i` int(11) default NULL
) ENGINE=ndbcluster DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

To check that your nodes were set up properly, start the management client:

shell> ndb_mgm

Use the SHOW command from within the management client to obtain a report on the cluster's status:

ndb_mgm> SHOW
Cluster Configuration
---------------------
[ndbd(NDB)]     1 node(s)
id=2    @127.0.0.1  (Version: 5.5.20-ndb-7.2.5, Nodegroup: 0, Master)

[ndb_mgmd(MGM)] 1 node(s)
id=1    @127.0.0.1  (Version: 5.5.20-ndb-7.2.5)

[mysqld(API)]   3 node(s)
id=3    @127.0.0.1  (Version: 5.5.20-ndb-7.2.5)
id=4 (not connected, accepting connect from any host)
id=5 (not connected, accepting connect from any host)

At this point, you have successfully set up a working MySQL Cluster. You can now store data in the cluster by using any table created with ENGINE=NDBCLUSTER or its alias ENGINE=NDB.

16.3.2. MySQL Cluster Configuration Files

Configuring MySQL Cluster requires working with two files:

  • my.cnf: Specifies options for all MySQL Cluster executables. This file, with which you should be familiar with from previous work with MySQL, must be accessible by each executable running in the cluster.

  • config.ini: This file, sometimes known as the global configuration file, is read only by the MySQL Cluster management server, which then distributes the information contained therein to all processes participating in the cluster. config.ini contains a description of each node involved in the cluster. This includes configuration parameters for data nodes and configuration parameters for connections between all nodes in the cluster. For a quick reference to the sections that can appear in this file, and what sorts of configuration parameters may be placed in each section, see Sections of the config.ini File.

Caching of configuration data.  In MySQL Cluster NDB 7.2, MySQL Cluster uses stateful configuration. Rather than reading the global configuration file every time the management server is restarted, the management server caches the configuration the first time it is started, and thereafter, the global configuration file is read only when one of the following conditions is true:

  • The management server is started using the --initial option.  In this case, the global configuration file is re-read, any existing cache files are deleted, and the management server creates a new configuration cache.

  • The management server is started using the --reload option.  In this case, the management server compares its cache with the global configuration file. If they differ, the management server creates a new configuration cache; any existing configuration cache is preserved, but not used. If the management server's cache and the global configuration file contain the same configuration data, then the existing cache is used, and no new cache is created.

  • The management server is started using a --config-cache option.  This option can be used to force the management server to bypass configuration caching altogether. In this case, the management server ignores any configuration files that may be present, always reading its configuration data from the config.ini file instead.

  • No configuration cache is found.  In this case, the management server reads the global configuration file and creates a cache containing the same configuration data as found in the file.

Configuration cache files.  The management server by default creates configuration cache files in a directory named mysql-cluster in the MySQL installation directory. (If you build MySQL Cluster from source on a Unix system, the default location is /usr/local/mysql-cluster.) This can be overridden at run time by starting the management server with the --configdir option. Configuration cache files are binary files named according to the pattern ndb_node_id_config.bin.seq_id, where node_id is the management server's node ID in the cluster, and seq_id is a cache idenitifer. Cache files are numbered sequentially using seq_id, in the order in which they are created. The management server uses the latest cache file as determined by the seq_id.

Замечание

It is possible to roll back to a previous configuration by deleting later configuration cache files, or by renaming an earlier cache file so that it has a higher seq_id. However, since configuration cache files are written in a binary format, you should not attempt to edit their contents by hand.

For more information about the --configdir, --initial, and --reload options for the MySQL Cluster management server, see Section 16.4.4, “ndb_mgmd — The MySQL Cluster Management Server Daemon”.

We are continuously making improvements in Cluster configuration and attempting to simplify this process. Although we strive to maintain backward compatibility, there may be times when introduce an incompatible change. In such cases we will try to let Cluster users know in advance if a change is not backward compatible. If you find such a change and we have not documented it, please report it in the MySQL bugs database using the instructions given in Section 1.7, “How to Report Bugs or Problems”.

16.3.2.1. MySQL Cluster Configuration: Basic Пример

To support MySQL Cluster, you will need to update my.cnf as shown in the following example. You may also specify these parameters on the command line when invoking the executables.

Замечание

The options shown here should not be confused with those that are used in config.ini global configuration files. Global configuration options are discussed later in this section.

# my.cnf
# example additions to my.cnf for MySQL Cluster
# (valid in MySQL 5.5)

# enable ndbcluster storage engine, and provide connectstring for
# management server host (default port is 1186)
[mysqld]
ndbcluster
ndb-connectstring=ndb_mgmd.mysql.com

# provide connectstring for management server host (default port: 1186)
[ndbd]
connect-string=ndb_mgmd.mysql.com

# provide connectstring for management server host (default port: 1186)
[ndb_mgm]
connect-string=ndb_mgmd.mysql.com

# provide location of cluster configuration file
[ndb_mgmd]
config-file=/etc/config.ini

(For more information on connectstrings, see Section 16.3.2.3, “The MySQL Cluster Connectstring”.)

# my.cnf
# example additions to my.cnf for MySQL Cluster
# (will work on all versions)

# enable ndbcluster storage engine, and provide connectstring for management
# server host to the default port 1186
[mysqld]
ndbcluster
ndb-connectstring=ndb_mgmd.mysql.com:1186
Important

Once you have started a mysqld process with the NDBCLUSTER and ndb-connectstring parameters in the [mysqld] in the my.cnf file as shown previously, you cannot execute any CREATE TABLE or ALTER TABLE statements without having actually started the cluster. Otherwise, these statements will fail with an error. This is by design.

You may also use a separate [mysql_cluster] section in the cluster my.cnf file for settings to be read and used by all executables:

# cluster-specific settings
[mysql_cluster]
ndb-connectstring=ndb_mgmd.mysql.com:1186

For additional NDB variables that can be set in the my.cnf file, see Section 16.3.4.3, “MySQL Cluster System Variables”.

The MySQL Cluster global configuration file is named config.ini by default. It is read by ndb_mgmd at startup and can be placed anywhere. Its location and name are specified by using --config-file=path_name on the ndb_mgmd command line. If the configuration file is not specified, ndb_mgmd by default tries to read a file named config.ini located in the current working directory.

The global configuration file for MySQL Cluster uses INI format, which consists of sections preceded by section headings (surrounded by square brackets), followed by the appropriate parameter names and values. One deviation from the standard INI format is that the parameter name and value can be separated by a colon (“:”) as well as the equal sign (“=”); however, the equal sign is preferred. Another deviation is that sections are not uniquely identified by section name. Instead, unique sections (such as two different nodes of the same type) are identified by a unique ID specified as a parameter within the section.

Default values are defined for most parameters, and can also be specified in config.ini. To create a default value section, simply add the word default to the section name. For example, an [ndbd] section contains parameters that apply to a particular data node, whereas an [ndbd default] section contains parameters that apply to all data nodes. Suppose that all data nodes should use the same data memory size. To configure them all, create an [ndbd default] section that contains a DataMemory line to specify the data memory size.

Замечание

In some older releases of MySQL Cluster, there was no default value for NoOfReplicas, which always had to be specified explicitly in the [ndbd default] section. Although this parameter now has a default value of 2, which is the recommended setting in most common usage scenarios, it is still recommended practice to set this parameter explicitly.

The global configuration file must define the computers and nodes involved in the cluster and on which computers these nodes are located. An example of a simple configuration file for a cluster consisting of one management server, two data nodes and two MySQL servers is shown here:

# file "config.ini" - 2 data nodes and 2 SQL nodes
# This file is placed in the startup directory of ndb_mgmd (the
# management server)
# The first MySQL Server can be started from any host. The second
# can be started only on the host mysqld_5.mysql.com

[ndbd default]
NoOfReplicas= 2
DataDir= /var/lib/mysql-cluster

[ndb_mgmd]
Hostname= ndb_mgmd.mysql.com
DataDir= /var/lib/mysql-cluster

[ndbd]
HostName= ndbd_2.mysql.com

[ndbd]
HostName= ndbd_3.mysql.com

[mysqld]
[mysqld]
HostName= mysqld_5.mysql.com
Замечание

The preceding example is intended as a minimal starting configuration for purposes of familiarization with MySQL Cluster, and is almost certain not to be sufficient for production settings. See Section 16.3.2.2, “Recommended Starting Configuration for MySQL Cluster”, which provides a more complete example starting configuration.

Each node has its own section in the config.ini file. For example, this cluster has two data nodes, so the preceding configuration file contains two [ndbd] sections defining these nodes.

Замечание

Do not place comments on the same line as a section heading in the config.ini file; this causes the management server not to start because it cannot parse the configuration file in such cases.

Sections of the config.ini File

There are six different sections that you can use in the config.ini configuration file, as described in the following list:

You can define default values for each section. All Cluster parameter names are case-insensitive, which differs from parameters specified in my.cnf or my.ini files.

16.3.2.2. Recommended Starting Configuration for MySQL Cluster

Achieving the best performance from a MySQL Cluster depends on a number of factors including the following:

  • MySQL Cluster software version

  • Numbers of data nodes and SQL nodes

  • Hardware

  • Operating system

  • Amount of data to be stored

  • Size and type of load under which the cluster is to operate

Therefore, obtaining an optimum configuration is likely to be an iterative process, the outcome of which can vary widely with the specifics of each MySQL Cluster deployment. Changes in configuration are also likely to be indicated when changes are made in the platform on which the cluster is run, or in applications that use the MySQL Cluster's data. For these reasons, it is not possible to offer a single configuration that is ideal for all usage scenarios. However, in this section, we provide a recommended base configuration.

Starting config.ini file.  The following config.ini file is a recommended starting point for configuring a cluster running MySQL Cluster NDB 7.2:

# TCP PARAMETERS

[tcp default]SendBufferMemory=2M
ReceiveBufferMemory=2M

# Increasing the sizes of these 2 buffers beyond the default values
# helps prevent bottlenecks due to slow disk I/O.

# MANAGEMENT NODE PARAMETERS

[ndb_mgmd default]
DataDir=path/to/management/server/data/directory

# It is possible to use a different data directory for each management
# server, but for ease of administration it is preferable to be
# consistent.

[ndb_mgmd]
HostName=management-server-A-hostname
# NodeId=management-server-A-nodeid

[ndb_mgmd]
HostName=management-server-B-hostname
# NodeId=management-server-B-nodeid

# Using 2 management servers helps guarantee that there is always an
# arbitrator in the event of network partitioning, and so is
# recommended for high availability. Each management server must be
# identified by a HostName. You may for the sake of convenience specify
# a NodeId for any management server, although one will be allocated
# for it automatically; if you do so, it must be in the range 1-255
# inclusive and must be unique among all IDs specified for cluster
# nodes.

# DATA NODE PARAMETERS

[ndbd default]
NoOfReplicas=2

# Using 2 replicas is recommended to guarantee availability of data; 
# using only 1 replica does not provide any redundancy, which means 
# that the failure of a single data node causes the entire cluster to 
# shut down. We do not recommend using more than 2 replicas, since 2 is 
# sufficient to provide high availability, and we do not currently test 
# with greater values for this parameter.

LockPagesInMainMemory=1

# On Linux and Solaris systems, setting this parameter locks data node
# processes into memory. Doing so prevents them from swapping to disk,
# which can severely degrade cluster performance.

DataMemory=3072M
IndexMemory=384M

# The values provided for DataMemory and IndexMemory assume 4 GB RAM
# per data node. However, for best results, you should first calculate
# the memory that would be used based on the data you actually plan to
# store (you may find the ndb_size.pl utility helpful in estimating
# this), then allow an extra 20% over the calculated values. Naturally,
# you should ensure that each data node host has at least as much
# physical memory as the sum of these two values.

# ODirect=1

# Enabling this parameter causes NDBCLUSTER to try using O_DIRECT
# writes for local checkpoints and redo logs; this can reduce load on
# CPUs. We recommend doing so when using MySQL Cluster on systems running 
# Linux kernel 2.6 or later.

NoOfFragmentLogFiles=300
DataDir=path/to/data/node/data/directory
MaxNoOfConcurrentOperations=100000

SchedulerSpinTimer=400
SchedulerExecutionTimer=100
RealTimeScheduler=1
# Setting these parameters allows you to take advantage of real-time scheduling
# of NDBCLUSTER threads to get higher throughput.

TimeBetweenGlobalCheckpoints=1000
TimeBetweenEpochs=200
DiskCheckpointSpeed=10M
DiskCheckpointSpeedInRestart=100M
RedoBuffer=32M

# CompressedLCP=1
# CompressedBackup=1
# Enabling CompressedLCP and CompressedBackup causes, respectively, local
checkpoint files and backup files to be compressed, which can result in a space
savings of up to 50% over noncompressed LCPs and backups.

# MaxNoOfLocalScans=64
MaxNoOfTables=1024
MaxNofOfOrderedIndexes=256

[ndbd]
HostName=data-node-A-hostname
# NodeId=data-node-A-nodeid

LockExecuteThreadToCPU=1
LockMaintThreadsToCPU=0
# On systems with multiple CPUs, these parameters can be used to lock NDBCLUSTER
# threads to specific CPUs

[ndbd]
HostName=data-node-B-hostname
# NodeId=data-node-B-nodeid

LockExecuteThreadToCPU=1
LockMaintThreadsToCPU=0

# You must have an [ndbd] section for every data node in the cluster;
# each of these sections must include a HostName. Each section may
# optionally include a NodeId for convenience, but in most cases, it is
# sufficient to allow the cluster to allocate node IDs dynamically. If
# you do specify the node ID for a data node, it must be in the range 1
# to 48 inclusive and must be unique among all IDs specified for
# cluster nodes.

# SQL NODE / API NODE PARAMETERS

[mysqld]
# HostName=sql-node-A-hostname
# NodeId=sql-node-A-nodeid

[mysqld]

[mysqld]

# Each API or SQL node that connects to the cluster requires a [mysqld]
# or [api] section of its own. Each such section defines a connection
# “slot”; you should have at least as many of these sections in the
# config.ini file as the total number of API nodes and SQL nodes that
# you wish to have connected to the cluster at any given time. There is
# no performance or other penalty for having extra slots available in
# case you find later that you want or need more API or SQL nodes to
# connect to the cluster at the same time.
# If no HostName is specified for a given [mysqld] or [api] section,
# then any API or SQL node may use that slot to connect to the
# cluster. You may wish to use an explicit HostName for one connection slot
# to guarantee that an API or SQL node from that host can always
# connect to the cluster. If you wish to prevent API or SQL nodes from
# connecting from other than a desired host or hosts, then use a
# HostName for every [mysqld] or [api] section in the config.ini file.
# You can if you wish define a node ID (NodeId parameter) for any API or
# SQL node, but this is not necessary; if you do so, it must be in the
# range 1 to 255 inclusive and must be unique among all IDs specified
# for cluster nodes.

Recommended my.cnf options for SQL nodes.  MySQL Servers acting as MySQL Cluster SQL nodes must always be started with the --ndbcluster and --ndb-connectstring options, either on the command line or in my.cnf. In addition, set the following options for all mysqld processes in the cluster, unless your setup requires otherwise:

  • --ndb-use-exact-count=0

  • --ndb-index-stat-enable=0

  • --ndb-force-send=1

  • --engine-condition-pushdown=1

16.3.2.3. The MySQL Cluster Connectstring

With the exception of the MySQL Cluster management server (ndb_mgmd), each node that is part of a MySQL Cluster requires a connectstring that points to the management server's location. This connectstring is used in establishing a connection to the management server as well as in performing other tasks depending on the node's role in the cluster. The syntax for a connectstring is as follows:

[nodeid=node_id, ]host-definition[, host-definition[, ...]]

host-definition:
    host_name[:port_number]

node_id is an integer larger than 1 which identifies a node in config.ini. host_name is a string representing a valid Internet host name or IP address. port_number is an integer referring to a TCP/IP port number.

example 1 (long):    "nodeid=2,myhost1:1100,myhost2:1100,192.168.0.3:1200"
example 2 (short):   "myhost1"

localhost:1186 is used as the default connectstring value if none is provided. If port_num is omitted from the connectstring, the default port is 1186. This port should always be available on the network because it has been assigned by IANA for this purpose (see http://www.iana.org/assignments/port-numbers for details).

By listing multiple host definitions, it is possible to designate several redundant management servers. A MySQL Cluster data or API node attempts to contact successive management servers on each host in the order specified, until a successful connection has been established.

It is also possible to specify in a connectstring one or more bind addresses to be used by nodes having multiple network interfaces for connecting to management servers. A bind address consists of a hostname or network address and an optional port number. This enhanced syntax for connectstrings is shown here:

[nodeid=node_id, ]
    [bind-address=host-definition, ]
    host-definition[; bind-address=host-definition]
    host-definition[; bind-address=host-definition]
    [, ...]]

host-definition:
    host_name[:port_number]

If a single bind address is used in the connectstring prior to specifying any management hosts, then this address is used as the default for connecting to any of them (unless overridden for a given management server; see later in this section for an example). For example, the following connectstring causes the node to use 192.168.178.242 regardless of the management server to which it connects:

bind-address=192.168.178.242, poseidon:1186, perch:1186

If a bind address is specified following a management host definition, then it is used only for connecting to that management node. Consider the following connectstring:

poseidon:1186;bind-address=localhost, perch:1186;bind-address=192.168.178.242

In this case, the node uses localhost to connect to the management server running on the host named poseidon and 192.168.178.242 to connect to the management server running on the host named perch.

You can specify a default bind address and then override this default for one or more specific management hosts. In the following example, localhost is used for connecting to the management server running on host poseidon; since 192.168.178.242 is specified first (before any management server definitions), it is the default bind address and so is used for connecting to the management servers on hosts perch and orca:

bind-address=192.168.178.242,poseidon:1186;bind-address=localhost,perch:1186,orca:2200

There are a number of different ways to specify the connectstring:

  • Each executable has its own command-line option which enables specifying the management server at startup. (See the documentation for the respective executable.)

  • It is also possible to set the connectstring for all nodes in the cluster at once by placing it in a [mysql_cluster] section in the management server's my.cnf file.

  • For backward compatibility, two other options are available, using the same syntax:

    1. Set the NDB_CONNECTSTRING environment variable to contain the connectstring.

    2. Write the connectstring for each executable into a text file named Ndb.cfg and place this file in the executable's startup directory.

    However, these are now deprecated and should not be used for new installations.

The recommended method for specifying the connectstring is to set it on the command line or in the my.cnf file for each executable.

16.3.2.4. Defining Computers in a MySQL Cluster

The [computer] section has no real significance other than serving as a way to avoid the need of defining host names for each node in the system. All parameters mentioned here are required.

  • Id

    Restart Typeinitial, node
     Permitted Values
    Typestring
    Default
    Range ..

    This is a unique identifier, used to refer to the host computer elsewhere in the configuration file.

    Important

    The computer ID is not the same as the node ID used for a management, API, or data node. Unlike the case with node IDs, you cannot use NodeId in place of Id in the [computer] section of the config.ini file.

  • HostName

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    This is the computer's hostname or IP address.

16.3.2.5. Defining a MySQL Cluster Management Server

The [ndb_mgmd] section is used to configure the behavior of the management server. [mgm] can be used as an alias; the two section names are equivalent. All parameters in the following list are optional and assume their default values if omitted.

Замечание

If neither the ExecuteOnComputer nor the HostName parameter is present, the default value localhost will be assumed for both.

  • Id

    Deprecated5.1.51-ndb-7.1.9
    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 63

    Each node in the cluster has a unique identity. For a management node, this is represented by an integer value in the range 1 to 255, inclusive. This ID is used by all internal cluster messages for addressing the node, and so must be unique for each MySQL Cluster node, regardless of the type of node.

    Замечание

    Data node IDs must be less than 49. If you plan to deploy a large number of data nodes, it is a good idea to limit the node IDs for management nodes (and API nodes) to values greater than 48.

    The use of the Id parameter for identifying management nodes is deprecated in favor of NodeId. Although Id continues to be supported for backward compatibility, it now generates a warning and is subject to removal in a future version of MySQL Cluster.

  • NodeId

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 63

    Each node in the cluster has a unique identity. For a management node, this is represented by an integer value in the range 1 to 255 inclusive. This ID is used by all internal cluster messages for addressing the node, and so must be unique for each MySQL Cluster node, regardless of the type of node.

    Замечание

    Data node IDs must be less than 49. If you plan to deploy a large number of data nodes, it is a good idea to limit the node IDs for management nodes (and API nodes) to values greater than 48.

    NodeId is the preferred parameter name to use when identifying management nodes. Although the older Id continues to be supported for backward compatibility, it is now deprecated and generates a warning when used; it is also subject to removal in a future MySQL Cluster release.

  • ExecuteOnComputer

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    This refers to the Id set for one of the computers defined in a [computer] section of the config.ini file.

  • PortNumber

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1186
    Range0 .. 64K

    This is the port number on which the management server listens for configuration requests and management commands.

  • HostName

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    Specifying this parameter defines the hostname of the computer on which the management node is to reside. To specify a hostname other than localhost, either this parameter or ExecuteOnComputer is required.

  • LogDestination

    Restart Typenode
     Permitted Values
    Typestring
    DefaultFILE:filename=ndb_nodeid_cluster.log,maxsize=1000000,maxfiles=6
    Range ..

    This parameter specifies where to send cluster logging information. There are three options in this regard—CONSOLE, SYSLOG, and FILE—with FILE being the default:

    • CONSOLE outputs the log to stdout:

      CONSOLE
    • SYSLOG sends the log to a syslog facility, possible values being one of auth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, or local7.

      Замечание

      Not every facility is necessarily supported by every operating system.

      SYSLOG:facility=syslog
    • FILE pipes the cluster log output to a regular file on the same machine. The following values can be specified:

      • filename: The name of the log file.

      • maxsize: The maximum size (in bytes) to which the file can grow before logging rolls over to a new file. When this occurs, the old log file is renamed by appending .N to the file name, where N is the next number not yet used with this name.

      • maxfiles: The maximum number of log files.

      FILE:filename=cluster.log,maxsize=1000000,maxfiles=6

      The default value for the FILE parameter is FILE:filename=ndb_node_id_cluster.log,maxsize=1000000,maxfiles=6, where node_id is the ID of the node.

    It is possible to specify multiple log destinations separated by semicolons as shown here:

    CONSOLE;SYSLOG:facility=local0;FILE:filename=/var/log/mgmd
  • ArbitrationRank

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1
    Range0 .. 2

    This parameter is used to define which nodes can act as arbitrators. Only management nodes and SQL nodes can be arbitrators. ArbitrationRank can take one of the following values:

    • 0: The node will never be used as an arbitrator.

    • 1: The node has high priority; that is, it will be preferred as an arbitrator over low-priority nodes.

    • 2: Indicates a low-priority node which be used as an arbitrator only if a node with a higher priority is not available for that purpose.

    Normally, the management server should be configured as an arbitrator by setting its ArbitrationRank to 1 (the default for management nodes) and those for all SQL nodes to 0 (the default for SQL nodes).

    You can disable arbitration completely either by setting ArbitrationRank to 0 on all management and SQL nodes, or by setting the Arbitration parameter in the [ndbd default] section of the config.ini global configuration file. Setting Arbitration causes any settings for ArbitrationRank to be disregarded.

  • ArbitrationDelay

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    An integer value which causes the management server's responses to arbitration requests to be delayed by that number of milliseconds. By default, this value is 0; it is normally not necessary to change it.

  • DataDir

    Restart Typenode
     Permitted Values
    Typestring
    Default.
    Range ..

    This specifies the directory where output files from the management server will be placed. These files include cluster log files, process output files, and the daemon's process ID (PID) file. (For log files, this location can be overridden by setting the FILE parameter for LogDestination as discussed previously in this section.)

    The default value for this parameter is the directory in which ndb_mgmd is located.

  • HeartbeatThreadPriority

    Set the scheduling policy and priority of heartbeat threads for management and API nodes.

    The syntax for setting this parameter is shown here:

    HeartbeatThreadPriority = policy[, priority]
    
    policy:
      {FIFO | RR}
    

    When setting this parameter, you must specify a policy. This is one of FIFO (first in, first out) or RR (round robin). The policy value is followed optionally by the priority (an integer).

  • TotalSendBufferMemory

    This parameter is available beginning with MySQL Cluster NDB 6.4.0. It is used to determine the total amount of memory to allocate on this node for shared send buffer memory among all configured transporters.

    If this parameter is set, its minimum permitted value is 256KB; the maxmimum is 4294967039. For more detailed information about the behavior and use of TotalSendBufferMemory and configuring send buffer memory parameters, see Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”.

Замечание

After making changes in a management node's configuration, it is necessary to perform a rolling restart of the cluster for the new configuration to take effect.

To add new management servers to a running MySQL Cluster, it is also necessary to perform a rolling restart of all cluster nodes after modifying any existing config.ini files. For more information about issues arising when using multiple management nodes, see Section 16.1.6.10, “Limitations Relating to Multiple MySQL Cluster Nodes”.

16.3.2.6. Defining MySQL Cluster Data Nodes

The [ndbd] and [ndbd default] sections are used to configure the behavior of the cluster's data nodes.

[ndbd] and [ndbd default] are always used as the section names whether you are using ndbd or ndbmtd binaries for the data node processes.

There are many parameters which control buffer sizes, pool sizes, timeouts, and so forth. The only mandatory parameter is either one of ExecuteOnComputer or HostName; this must be defined in the local [ndbd] section.

The parameter NoOfReplicas should be defined in the [ndbd default] section, as it is common to all Cluster data nodes. It is not strictly necessary to set NoOfReplicas, but it is good practice to set it explicitly.

Most data node parameters are set in the [ndbd default] section. Only those parameters explicitly stated as being able to set local values are permitted to be changed in the [ndbd] section. Where present, HostName, NodeId and ExecuteOnComputer must be defined in the local [ndbd] section, and not in any other section of config.ini. In other words, settings for these parameters are specific to one data node.

For those parameters affecting memory usage or buffer sizes, it is possible to use K, M, or G as a suffix to indicate units of 1024, 1024×1024, or 1024×1024×1024. (For example, 100K means 100 × 1024 = 102400.) Parameter names and values are currently case-sensitive.

Information about configuration parameters specific to MySQL Cluster Disk Data tables can be found later in this section.

All of these parameters also apply to ndbmtd (the multi-threaded version of ndbd). An additional data node configuration parameter MaxNoOfExecutionThreads applies to ndbmtd only, and has no effect when used with ndbd. For more information, see Section 16.4.3, “ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)”.

Identifying data nodes.  The NodeId or Id value (that is, the data node identifier) can be allocated on the command line when the node is started or in the configuration file.

  • Id

    Deprecated5.1.51-ndb-7.1.9
    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 48

    A unique node ID is used as the node's address for all cluster internal messages. For data nodes, this is an integer in the range 1 to 48 inclusive. Each node in the cluster must have a unique identifier.

    NodeId is the preferred parameter name to use when identifying data nodes. Although the older Id is still supported for backward compatibility, it is now deprecated, and generates a warning when used. Id is also subject to removal in a future MySQL Cluster release.

  • NodeId

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 48

    A unique node ID is used as the node's address for all cluster internal messages. For data nodes, this is an integer in the range 1 to 48 inclusive. Each node in the cluster must have a unique identifier.

    NodeId is the preferred parameter name to use when identifying data nodes. Although Id continues to be supported for backward compatibility, it is now deprecated, generates a warning when used, and is subject to removal in a future version of MySQL Cluster.

  • ExecuteOnComputer

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    This refers to the Id set for one of the computers defined in a [computer] section.

  • HostName

    Restart Typesystem
     Permitted Values
    Typestring
    Defaultlocalhost
    Range ..

    Specifying this parameter defines the hostname of the computer on which the data node is to reside. To specify a hostname other than localhost, either this parameter or ExecuteOnComputer is required.

  • ServerPort

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 64K

    Each node in the cluster uses a port to connect to other nodes. By default, this port is allocated dynamically in such a way as to ensure that no two nodes on the same host computer receive the same port number, so it should normally not be necessary to specify a value for this parameter.

    However, if you need to be able to open specific ports in a firewall to permit communication between data nodes and API nodes (including SQL nodes), you can set this parameter to the number of the desired port in an [ndbd] section or (if you need to do this for multiple data nodes) the [ndbd default] section of the config.ini file, and then open the port having that number for incoming connections from SQL nodes, API nodes, or both.

    Замечание

    Connections from data nodes to management nodes is done using the ndb_mgmd management port (the management server's PortNumber; see Section 16.3.2.5, “Defining a MySQL Cluster Management Server”) so outgoing connections to that port from any data nodes should always be permitted.

  • TcpBind_INADDR_ANY

    Setting this parameter to TRUE or 1 binds IP_ADDR_ANY so that connections can be made from anywhere (for autogenerated connections). The default is FALSE (0).

  • NodeGroup

    Restart Typeinitial, system
     Permitted Values
    Typenumeric
    Default
    Range0 .. 65536

    This parameter can be used to assign a data node to a specific node group. It is read only when the cluster is started for the first time, and cannot be used to reassign a data node to a different node group online. It is generally not desirable to use this parameter in the [ndbd default] section of the config.ini file, and care must be taken not to assign nodes to node groups in such a way that an invalid numbers of nodes are assigned to any node groups.

    The NodeGroup parameter is chiefly intended for use in adding a new node group to a running MySQL Cluster without having to perform a rolling restart. For this purpose, you should set it to 65536 (the maximum value). You are not required to set a NodeGroup value for all cluster data nodes, only for those nodes which are to be started and added to the cluster as a new node group at a later time. For more information, see Section 16.5.12.3, “Adding MySQL Cluster Data Nodes Online: Detailed Пример”.

  • NoOfReplicas

    Restart Typeinitial, system
     Permitted Values
    Typenumeric
    DefaultNone
    Range1 .. 4
     Permitted Values
    Typenumeric
    DefaultNone
    Range1 .. 4
     Permitted Values
    Typenumeric
    Default2
    Range1 .. 4
     Permitted Values
    Typenumeric
    Default2
    Range1 .. 4

    This global parameter can be set only in the [ndbd default] section, and defines the number of replicas for each table stored in the cluster. This parameter also specifies the size of node groups. A node group is a set of nodes all storing the same information.

    Node groups are formed implicitly. The first node group is formed by the set of data nodes with the lowest node IDs, the next node group by the set of the next lowest node identities, and so on. By way of example, assume that we have 4 data nodes and that NoOfReplicas is set to 2. The four data nodes have node IDs 2, 3, 4 and 5. Then the first node group is formed from nodes 2 and 3, and the second node group by nodes 4 and 5. It is important to configure the cluster in such a manner that nodes in the same node groups are not placed on the same computer because a single hardware failure would cause the entire cluster to fail.

    If no node IDs are provided, the order of the data nodes will be the determining factor for the node group. Whether or not explicit assignments are made, they can be viewed in the output of the management client's SHOW command.

    The default value for NoOfReplicas is 2, which is the recommended setting in most common usage scenarios.

    The maximum possible value is 4; currently, only the values 1 and 2 are actually supported.

    Important

    Setting NoOfReplicas to 1 means that there is only a single copy of all Cluster data; in this case, the loss of a single data node causes the cluster to fail because there are no additional copies of the data stored by that node.

    The value for this parameter must divide evenly into the number of data nodes in the cluster. For example, if there are two data nodes, then NoOfReplicas must be equal to either 1 or 2, since 2/3 and 2/4 both yield fractional values; if there are four data nodes, then NoOfReplicas must be equal to 1, 2, or 4.

  • DataDir

    Restart Typeinitial, node
     Permitted Values
    Typestring
    Default.
    Range ..

    This parameter specifies the directory where trace files, log files, pid files and error logs are placed.

    The default is the data node process working directory.

  • FileSystemPath

    Restart Typeinitial, node
     Permitted Values
    Typestring
    DefaultDataDir
    Range ..

    This parameter specifies the directory where all files created for metadata, REDO logs, UNDO logs (for Disk Data tables), and data files are placed. The default is the directory specified by DataDir.

    Замечание

    This directory must exist before the ndbd process is initiated.

    The recommended directory hierarchy for MySQL Cluster includes /var/lib/mysql-cluster, under which a directory for the node's file system is created. The name of this subdirectory contains the node ID. For example, if the node ID is 2, this subdirectory is named ndb_2_fs.

  • BackupDataDir

    Restart Typeinitial, node
     Permitted Values
    Typestring
    DefaultFileSystemPath
    Range ..

    This parameter specifies the directory in which backups are placed.

    Important

    The string '/BACKUP' is always appended to this value. For example, if you set the value of BackupDataDir to /var/lib/cluster-data, then all backups are stored under /var/lib/cluster-data/BACKUP. This also means that the effective default backup location is the directory named BACKUP under the location specified by the FileSystemPath parameter.

Data Memory, Index Memory, and String Memory

DataMemory and IndexMemory are [ndbd] parameters specifying the size of memory segments used to store the actual records and their indexes. In setting values for these, it is important to understand how DataMemory and IndexMemory are used, as they usually need to be updated to reflect actual usage by the cluster:

  • DataMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default80M
    Range1M .. 1024G

    This parameter defines the amount of space (in bytes) available for storing database records. The entire amount specified by this value is allocated in memory, so it is extremely important that the machine has sufficient physical memory to accommodate it.

    The memory allocated by DataMemory is used to store both the actual records and indexes. There is a 16-byte overhead on each record; an additional amount for each record is incurred because it is stored in a 32KB page with 128 byte page overhead (see below). There is also a small amount wasted per page due to the fact that each record is stored in only one page.

    For variable-size table attributes, the data is stored on separate datapages, allocated from DataMemory. Variable-length records use a fixed-size part with an extra overhead of 4 bytes to reference the variable-size part. The variable-size part has 2 bytes overhead plus 2 bytes per attribute.

    The maximum record size is 14000 bytes.

    The memory space defined by DataMemory is also used to store ordered indexes, which use about 10 bytes per record. Each table row is represented in the ordered index. A common error among users is to assume that all indexes are stored in the memory allocated by IndexMemory, but this is not the case: Only primary key and unique hash indexes use this memory; ordered indexes use the memory allocated by DataMemory. However, creating a primary key or unique hash index also creates an ordered index on the same keys, unless you specify USING HASH in the index creation statement. This can be verified by running ndb_desc -d db_name table_name in the management client.

    Currently, MySQL Cluster can use a maximum of 512 MB for hash indexes per partition, which means in some cases it is possible to get Table is full errors in MySQL client applications even when ndb_mgm -e "ALL REPORT MEMORYUSAGE" shows significant free DataMemory. This can also pose a problem with data node restarts on nodes that are heavily loaded with data. You can force NDB to create extra partitions for MySQL Cluster tables and thus have more memory available for hash indexes by using the MAX_ROWS option for CREATE TABLE. In general, setting MAX_ROWS to twice the number of rows that you expect to store in the table should be sufficient. In MySQL Cluster 7.2.3 and later, you can also use the MinFreePct configuration parameter to help avoid problems with node restarts. (Bug #13436216)

    The memory space allocated by DataMemory consists of 32KB pages, which are allocated to table fragments. Each table is normally partitioned into the same number of fragments as there are data nodes in the cluster. Thus, for each node, there are the same number of fragments as are set in NoOfReplicas.

    Once a page has been allocated, it is currently not possible to return it to the pool of free pages, except by deleting the table. (This also means that DataMemory pages, once allocated to a given table, cannot be used by other tables.) Performing a data node recovery also compresses the partition because all records are inserted into empty partitions from other live nodes.

    The DataMemory memory space also contains UNDO information: For each update, a copy of the unaltered record is allocated in the DataMemory. There is also a reference to each copy in the ordered table indexes. Unique hash indexes are updated only when the unique index columns are updated, in which case a new entry in the index table is inserted and the old entry is deleted upon commit. For this reason, it is also necessary to allocate enough memory to handle the largest transactions performed by applications using the cluster. In any case, performing a few large transactions holds no advantage over using many smaller ones, for the following reasons:

    • Large transactions are not any faster than smaller ones

    • Large transactions increase the number of operations that are lost and must be repeated in event of transaction failure

    • Large transactions use more memory

    The default value for DataMemory is 80MB; the minimum is 1MB. There is no maximum size, but in reality the maximum size has to be adapted so that the process does not start swapping when the limit is reached. This limit is determined by the amount of physical RAM available on the machine and by the amount of memory that the operating system may commit to any one process. 32-bit operating systems are generally limited to 2–4GB per process; 64-bit operating systems can use more. For large databases, it may be preferable to use a 64-bit operating system for this reason.

  • IndexMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default18M
    Range1M .. 1T

    This parameter controls the amount of storage used for hash indexes in MySQL Cluster. Hash indexes are always used for primary key indexes, unique indexes, and unique constraints. Note that when defining a primary key and a unique index, two indexes will be created, one of which is a hash index used for all tuple accesses as well as lock handling. It is also used to enforce unique constraints.

    The size of the hash index is 25 bytes per record, plus the size of the primary key. For primary keys larger than 32 bytes another 8 bytes is added.

    The default value for IndexMemory is 18MB. The minimum is 1MB.

  • StringMemory

    Restart Typesystem
     Permitted Values (>= 5.5)
    Typenumeric
    Default25
    Range0 .. 4G

    This parameter determines how much memory is allocated for strings such as table names, and is specified in an [ndbd] or [ndbd default] section of the config.ini file. A value between 0 and 100 inclusive is interpreted as a percent of the maximum default value, which is calculated based on a number of factors including the number of tables, maximum table name size, maximum size of .FRM files, MaxNoOfTriggers, maximum column name size, and maximum default column value.

    A value greater than 100 is interpreted as a number of bytes.

    The default value is 25—that is, 25 percent of the default maximum.

    Under most circumstances, the default value should be sufficient, but when you have a great many Cluster tables (1000 or more), it is possible to get Error 773 Out of string memory, please modify StringMemory config parameter: Permanent error: Schema error, in which case you should increase this value. 25 (25 percent) is not excessive, and should prevent this error from recurring in all but the most extreme conditions.

The following example illustrates how memory is used for a table. Consider this table definition:

CREATE TABLE example (
  a INT NOT NULL,
  b INT NOT NULL,
  c INT NOT NULL,
  PRIMARY KEY(a),
  UNIQUE(b)
) ENGINE=NDBCLUSTER;

For each record, there are 12 bytes of data plus 12 bytes overhead. Having no nullable columns saves 4 bytes of overhead. In addition, we have two ordered indexes on columns a and b consuming roughly 10 bytes each per record. There is a primary key hash index on the base table using roughly 29 bytes per record. The unique constraint is implemented by a separate table with b as primary key and a as a column. This other table consumes an additional 29 bytes of index memory per record in the example table as well 8 bytes of record data plus 12 bytes of overhead.

Thus, for one million records, we need 58MB for index memory to handle the hash indexes for the primary key and the unique constraint. We also need 64MB for the records of the base table and the unique index table, plus the two ordered index tables.

You can see that hash indexes takes up a fair amount of memory space; however, they provide very fast access to the data in return. They are also used in MySQL Cluster to handle uniqueness constraints.

Currently, the only partitioning algorithm is hashing and ordered indexes are local to each node. Thus, ordered indexes cannot be used to handle uniqueness constraints in the general case.

An important point for both IndexMemory and DataMemory is that the total database size is the sum of all data memory and all index memory for each node group. Each node group is used to store replicated information, so if there are four nodes with two replicas, there will be two node groups. Thus, the total data memory available is 2 × DataMemory for each data node.

It is highly recommended that DataMemory and IndexMemory be set to the same values for all nodes. Data distribution is even over all nodes in the cluster, so the maximum amount of space available for any node can be no greater than that of the smallest node in the cluster.

DataMemory and IndexMemory can be changed, but decreasing either of these can be risky; doing so can easily lead to a node or even an entire MySQL Cluster that is unable to restart due to there being insufficient memory space. Increasing these values should be acceptable, but it is recommended that such upgrades are performed in the same manner as a software upgrade, beginning with an update of the configuration file, and then restarting the management server followed by restarting each data node in turn.

Beginning with MySQL Cluster NDB 7.2.3, a proportion (5% by default) of data node resources including DataMemory and IndexMemory is kept in reserve to insure that the data node does not exhaust its memory when performing a restart. This can be adjusted using the MinFreePct data node configuration parameter (default 5) introduced in the same version of MySQL Cluster.

Version Introduced5.5.17-ndb-7.2.3
Restart Typenode
 Permitted Values
Typenumeric
Default5
Range0 .. 100
 Permitted Values
Typenumeric
Default5
Range0 .. 100
 Permitted Values
Typenumeric
Default5
Range0 .. 100

Updates do not increase the amount of index memory used. Inserts take effect immediately; however, rows are not actually deleted until the transaction is committed.

Transaction parameters.  The next few [ndbd] parameters that we discuss are important because they affect the number of parallel transactions and the sizes of transactions that can be handled by the system. MaxNoOfConcurrentTransactions sets the number of parallel transactions possible in a node. MaxNoOfConcurrentOperations sets the number of records that can be in update phase or locked simultaneously.

Both of these parameters (especially MaxNoOfConcurrentOperations) are likely targets for users setting specific values and not using the default value. The default value is set for systems using small transactions, to ensure that these do not use excessive memory.

MaxDMLOperationsPerTransaction sets the maximum number of DML operations that can be performed in a given transaction.

  • MaxNoOfConcurrentTransactions

    Restart Typesystem
     Permitted Values
    Typenumeric
    Default4096
    Range32 .. 4G

    Each cluster data node requires a transaction record for each active transaction in the cluster. The task of coordinating transactions is distributed among all of the data nodes. The total number of transaction records in the cluster is the number of transactions in any given node times the number of nodes in the cluster.

    Transaction records are allocated to individual MySQL servers. Each connection to a MySQL server requires at least one transaction record, plus an additional transaction object per table accessed by that connection. This means that a reasonable minimum for this parameter is

    MaxNoOfConcurrentTransactions =
        (maximum number of tables accessed in any single transaction + 1)
        * number of cluster SQL nodes

    Suppose that there are 4 SQL nodes using the cluster. A single join involving 5 tables requires 6 transaction records; if there are 5 such joins in a transaction, then 5 * 6 = 30 transaction records are required for this transaction, per MySQL server, or 30 * 4 = 120 transaction records total.

    This parameter must be set to the same value for all cluster data nodes. This is due to the fact that, when a data node fails, the oldest surviving node re-creates the transaction state of all transactions that were ongoing in the failed node.

    Changing the value of MaxNoOfConcurrentTransactions requires a complete shutdown and restart of the cluster.

    The default value is 4096.

  • MaxNoOfConcurrentOperations

    Restart Typenode
     Permitted Values
    Typenumeric
    Default32K
    Range32 .. 4G

    It is a good idea to adjust the value of this parameter according to the size and number of transactions. When performing transactions of only a few operations each and not involving a great many records, there is no need to set this parameter very high. When performing large transactions involving many records need to set this parameter higher.

    Records are kept for each transaction updating cluster data, both in the transaction coordinator and in the nodes where the actual updates are performed. These records contain state information needed to find UNDO records for rollback, lock queues, and other purposes.

    This parameter should be set to the number of records to be updated simultaneously in transactions, divided by the number of cluster data nodes. For example, in a cluster which has four data nodes and which is expected to handle 1,000,000 concurrent updates using transactions, you should set this value to 1000000 / 4 = 250000.

    Read queries which set locks also cause operation records to be created. Some extra space is allocated within individual nodes to accommodate cases where the distribution is not perfect over the nodes.

    When queries make use of the unique hash index, there are actually two operation records used per record in the transaction. The first record represents the read in the index table and the second handles the operation on the base table.

    The default value is 32768.

    This parameter actually handles two values that can be configured separately. The first of these specifies how many operation records are to be placed with the transaction coordinator. The second part specifies how many operation records are to be local to the database.

    A very large transaction performed on an eight-node cluster requires as many operation records in the transaction coordinator as there are reads, updates, and deletes involved in the transaction. However, the operation records of the are spread over all eight nodes. Thus, if it is necessary to configure the system for one very large transaction, it is a good idea to configure the two parts separately. MaxNoOfConcurrentOperations will always be used to calculate the number of operation records in the transaction coordinator portion of the node.

    It is also important to have an idea of the memory requirements for operation records. These consume about 1KB per record.

  • MaxNoOfLocalOperations

    Restart Typenode
     Permitted Values
    Typenumeric
    DefaultUNDEFINED
    Range32 .. 4G

    By default, this parameter is calculated as 1.1 × MaxNoOfConcurrentOperations. This fits systems with many simultaneous transactions, none of them being very large. If there is a need to handle one very large transaction at a time and there are many nodes, it is a good idea to override the default value by explicitly specifying this parameter.

  • MaxDMLOperationsPerTransaction

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4294967295
    Range32 .. 4294967295
     Permitted Values
    Typenumeric
    Default4294967295
    Range32 .. 4294967295

    This parameter limits the size of a transaction. The transaction is aborted if it requires more than this many DML operations. The minimum number of operations per transaction is 32; however, you can set MaxDMLOperationsPerTransaction to 0 to disable any limitation on the number of DML operations per transaction. The maximum (and default) is 4294967295.

Transaction temporary storage.  The next set of [ndbd] parameters is used to determine temporary storage when executing a statement that is part of a Cluster transaction. All records are released when the statement is completed and the cluster is waiting for the commit or rollback.

The default values for these parameters are adequate for most situations. However, users with a need to support transactions involving large numbers of rows or operations may need to increase these values to enable better parallelism in the system, whereas users whose applications require relatively small transactions can decrease the values to save memory.

  • MaxNoOfConcurrentIndexOperations

    Restart Typenode
     Permitted Values
    Typenumeric
    Default8K
    Range0 .. 4G

    For queries using a unique hash index, another temporary set of operation records is used during a query's execution phase. This parameter sets the size of that pool of records. Thus, this record is allocated only while executing a part of a query. As soon as this part has been executed, the record is released. The state needed to handle aborts and commits is handled by the normal operation records, where the pool size is set by the parameter MaxNoOfConcurrentOperations.

    The default value of this parameter is 8192. Only in rare cases of extremely high parallelism using unique hash indexes should it be necessary to increase this value. Using a smaller value is possible and can save memory if the DBA is certain that a high degree of parallelism is not required for the cluster.

  • MaxNoOfFiredTriggers

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4000
    Range0 .. 4G

    The default value of MaxNoOfFiredTriggers is 4000, which is sufficient for most situations. In some cases it can even be decreased if the DBA feels certain the need for parallelism in the cluster is not high.

    A record is created when an operation is performed that affects a unique hash index. Inserting or deleting a record in a table with unique hash indexes or updating a column that is part of a unique hash index fires an insert or a delete in the index table. The resulting record is used to represent this index table operation while waiting for the original operation that fired it to complete. This operation is short-lived but can still require a large number of records in its pool for situations with many parallel write operations on a base table containing a set of unique hash indexes.

  • TransactionBufferMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1M
    Range1K .. 4G

    The memory affected by this parameter is used for tracking operations fired when updating index tables and reading unique indexes. This memory is used to store the key and column information for these operations. It is only very rarely that the value for this parameter needs to be altered from the default.

    The default value for TransactionBufferMemory is 1MB.

    Normal read and write operations use a similar buffer, whose usage is even more short-lived. The compile-time parameter ZATTRBUF_FILESIZE (found in ndb/src/kernel/blocks/Dbtc/Dbtc.hpp) set to 4000 × 128 bytes (500KB). A similar buffer for key information, ZDATABUF_FILESIZE (also in Dbtc.hpp) contains 4000 × 16 = 62.5KB of buffer space. Dbtc is the module that handles transaction coordination.

Scans and buffering.  There are additional [ndbd] parameters in the Dblqh module (in ndb/src/kernel/blocks/Dblqh/Dblqh.hpp) that affect reads and updates. These include ZATTRINBUF_FILESIZE, set by default to 10000 × 128 bytes (1250KB) and ZDATABUF_FILE_SIZE, set by default to 10000*16 bytes (roughly 156KB) of buffer space. To date, there have been neither any reports from users nor any results from our own extensive tests suggesting that either of these compile-time limits should be increased.

  • MaxNoOfConcurrentScans

    Restart Typenode
     Permitted Values
    Typenumeric
    Default256
    Range2 .. 500

    This parameter is used to control the number of parallel scans that can be performed in the cluster. Each transaction coordinator can handle the number of parallel scans defined for this parameter. Each scan query is performed by scanning all partitions in parallel. Each partition scan uses a scan record in the node where the partition is located, the number of records being the value of this parameter times the number of nodes. The cluster should be able to sustain MaxNoOfConcurrentScans scans concurrently from all nodes in the cluster.

    Scans are actually performed in two cases. The first of these cases occurs when no hash or ordered indexes exists to handle the query, in which case the query is executed by performing a full table scan. The second case is encountered when there is no hash index to support the query but there is an ordered index. Using the ordered index means executing a parallel range scan. The order is kept on the local partitions only, so it is necessary to perform the index scan on all partitions.

    The default value of MaxNoOfConcurrentScans is 256. The maximum value is 500.

  • MaxNoOfLocalScans

    Restart Typenode
     Permitted Values
    Typenumeric
    DefaultUNDEFINED
    Range32 .. 4G

    Specifies the number of local scan records if many scans are not fully parallelized. In MySQL Cluster NDB 7.2.0 and later, when the number of local scan records is not provided, it is calculated as 4 times the product of MaxNoOfConcurrentScans and the number of data nodes in the system. (Previously, it was calculated as the product of MaxNoOfConcurrentScans and the number of data nodes.) The minimum value is 32.

  • BatchSizePerLocalScan

    Restart Typenode
     Permitted Values (>= 5.5)
    Typenumeric
    Default256
    Range1 .. 992

    This parameter is used to calculate the number of lock records used to handle concurrent scan operations.

    The default value is 64; this value has a strong connection to the BatchSize defined in the SQL nodes.

  • LongMessageBuffer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1M
    Range512K .. 4G
     Permitted Values
    Typenumeric
    Default4M
    Range512K .. 4G

    This is an internal buffer used for passing messages within individual nodes and between nodes. The default is 4MB.

    This parameter seldom needs to be changed from the default.

  • MaxParallelScansPerFragment

    Restart Typenode
     Permitted Values
    Typenumeric
    Default32
    Range1 .. 1G
     Permitted Values
    Typenumeric
    Default32
    Range1 .. 1G
     Permitted Values
    Typenumeric
    Default256
    Range1 .. 1G

    It is possible to copnfigure the maximum number of parallel scans (TUP scans and TUX scans) allowed before they begin queuing for serial handling. You can increase this to take advantage of any unused CPU when performing large number of scans in parallel and improve their performance.

    Beginning with MySQL Cluster NDB 7.2.0, the default value for this parameter was increased from 32 to 256.

Memory Allocation

MaxAllocate

This is the maximum size of the memory unit to use when allocating memory for tables. In cases where NDB gives Out of memory errors, but it is evident by examining the cluster logs or the output of DUMP 1000 (see DUMP 1000) that all available memory has not yet been used, you can increase the value of this parameter (or MaxNoOfTables, or both) to cause NDB to make sufficient memory available.

Logging and checkpointing.  The following [ndbd] parameters control log and checkpoint behavior.

  • NoOfFragmentLogFiles

    Restart Typeinitial, node
     Permitted Values
    Typenumeric
    Default16
    Range3 .. 4G

    This parameter sets the number of REDO log files for the node, and thus the amount of space allocated to REDO logging. Because the REDO log files are organized in a ring, it is extremely important that the first and last log files in the set (sometimes referred to as the “head” and “tail” log files, respectively) do not meet. When these approach one another too closely, the node begins aborting all transactions encompassing updates due to a lack of room for new log records.

    A REDO log record is not removed until the required number of local checkpoints has been completed since that log record was inserted. (In MySQL Cluster NDB 7.2, only 2 local checkpoints are necessary). Checkpointing frequency is determined by its own set of configuration parameters discussed elsewhere in this chapter.

    The default parameter value is 16, which by default means 16 sets of 4 16MB files for a total of 1024MB. The size of the individual log files is configurable using the FragmentLogFileSize parameter. In scenarios requiring a great many updates, the value for NoOfFragmentLogFiles may need to be set as high as 300 or even higher to provide sufficient space for REDO logs.

    If the checkpointing is slow and there are so many writes to the database that the log files are full and the log tail cannot be cut without jeopardizing recovery, all updating transactions are aborted with internal error code 410 (Out of log file space temporarily). This condition prevails until a checkpoint has completed and the log tail can be moved forward.

    Important

    This parameter cannot be changed “on the fly”; you must restart the node using --initial. If you wish to change this value for all data nodes in a running cluster, you can do so using a rolling node restart (using --initial when starting each data node).

  • FragmentLogFileSize

    Restart Typeinitial, node
     Permitted Values
    Typenumeric
    Default16M
    Range4M .. 1G

    Setting this parameter enables you to control directly the size of redo log files. This can be useful in situations when MySQL Cluster is operating under a high load and it is unable to close fragment log files quickly enough before attempting to open new ones (only 2 fragment log files can be open at one time); increasing the size of the fragment log files gives the cluster more time before having to open each new fragment log file. The default value for this parameter is 16M.

    For more information about fragment log files, see the description for NoOfFragmentLogFiles.

  • InitFragmentLogFiles

    Restart Typeinitial, node
     Permitted Values
    Typestring
    Default
    Range ..

    By default, fragment log files are created sparsely when performing an initial start of a data node—that is, depending on the operating system and file system in use, not all bytes are necessarily written to disk. However, it is possible to override this behavior and force all bytes to be written, regardless of the platform and file system type being used, by means of this parameter. InitFragmentLogFiles takes either of two values:

    • SPARSE. Fragment log files are created sparsely. This is the default value.

    • FULL. Force all bytes of the fragment log file to be written to disk.

    Depending on your operating system and file system, setting InitFragmentLogFiles=FULL may help eliminate I/O errors on writes to the REDO log.

  • MaxNoOfOpenFiles

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range20 .. 4G

    This parameter sets a ceiling on how many internal threads to allocate for open files. Any situation requiring a change in this parameter should be reported as a bug.

    The default value is 0. However, the minimum value to which this parameter can be set is 20.

  • InitialNoOfOpenFiles

    Restart Typenode
     Permitted Values
    Typenumeric
    Default27
    Range20 .. 4G

    This parameter sets the initial number of internal threads to allocate for open files.

    The default value is 27.

  • MaxNoOfSavedMessages

    Restart Typenode
     Permitted Values
    Typenumeric
    Default25
    Range0 .. 4G

    This parameter sets the maximum number of trace files that are kept before overwriting old ones. Trace files are generated when, for whatever reason, the node crashes.

    The default is 25 trace files.

  • MaxLCPStartDelay

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 600
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 600

    In parallel data node recovery, only table data is actually copied and synchronized in parallel; synchronization of metadata such as dictionary and checkpoint information is done in a serial fashion. In addition, recovery of dictionary and checkpoint information cannot be executed in parallel with performing of local checkpoints. This means that, when starting or restarting many data nodes concurrently, data nodes may be forced to wait while a local checkpoint is performed, which can result in longer node recovery times.

    It is possible to force a delay in the local checkpoint to permit more (and possibly all) data nodes to complete metadata synchronization; once each data node's metadata synchronization is complete, all of the data nodes can recover table data in parallel, even while the local checkpoint is being executed. To force such a delay, set MaxLCPStartDelay, which determines the number of seconds the cluster can wait to begin a local checkpoint while data nodes continue to synchronize metadata. This parameter should be set in the [ndbd default] section of the config.ini file, so that it is the same for all data nodes. The maximum value is 600; the default is 0.

Metadata objects.  The next set of [ndbd] parameters defines pool sizes for metadata objects, used to define the maximum number of attributes, tables, indexes, and trigger objects used by indexes, events, and replication between clusters. Note that these act merely as “suggestions” to the cluster, and any that are not specified revert to the default values shown.

  • MaxNoOfAttributes

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1000
    Range32 .. 4G

    This parameter sets a suggested maximum number of attributes that can be defined in the cluster; like MaxNoOfTables, it is not intended to function as a hard upper limit.

    (In older MySQL Cluster releases, this parameter was sometimes treated as a hard limit for certain operations. This caused problems with MySQL Cluster Replication, when it was possible to create more tables than could be replicated, and sometimes led to confusion when it was possible [or not possible, depending on the circumstances] to create more than MaxNoOfAttributes attributes.)

    The default value is 1000, with the minimum possible value being 32. The maximum is 4294967039. Each attribute consumes around 200 bytes of storage per node due to the fact that all metadata is fully replicated on the servers.

    When setting MaxNoOfAttributes, it is important to prepare in advance for any ALTER TABLE statements that you might want to perform in the future. This is due to the fact, during the execution of ALTER TABLE on a Cluster table, 3 times the number of attributes as in the original table are used, and a good practice is to permit double this amount. For example, if the MySQL Cluster table having the greatest number of attributes (greatest_number_of_attributes) has 100 attributes, a good starting point for the value of MaxNoOfAttributes would be 6 * greatest_number_of_attributes = 600.

    You should also estimate the average number of attributes per table and multiply this by MaxNoOfTables. If this value is larger than the value obtained in the previous paragraph, you should use the larger value instead.

    Assuming that you can create all desired tables without any problems, you should also verify that this number is sufficient by trying an actual ALTER TABLE after configuring the parameter. If this is not successful, increase MaxNoOfAttributes by another multiple of MaxNoOfTables and test it again.

  • MaxNoOfTables

    Restart Typenode
     Permitted Values
    Typenumeric
    Default128
    Range8 .. 20320

    A table object is allocated for each table and for each unique hash index in the cluster. This parameter sets a suggested maximum number of table objects for the cluster as a whole; like MaxNoOfAttributes, it is not intended to function as a hard upper limit.

    (In older MySQL Cluster releases, this parameter was sometimes treated as a hard limit for certain operations. This caused problems with MySQL Cluster Replication, when it was possible to create more tables than could be replicated, and sometimes led to confusion when it was possible [or not possible, depending on the circumstances] to create more than MaxNoOfTables tables.)

    For each attribute that has a BLOB data type an extra table is used to store most of the BLOB data. These tables also must be taken into account when defining the total number of tables.

    The default value of this parameter is 128. The minimum is 8 and the maximum is 20320. Each table object consumes approximately 20KB per node.

    Замечание

    The sum of MaxNoOfTables, MaxNoOfOrderedIndexes, and MaxNoOfUniqueHashIndexes must not exceed 232 – 2 (4294967294).

  • MaxNoOfOrderedIndexes

    Restart Typenode
     Permitted Values
    Typenumeric
    Default128
    Range0 .. 4G

    For each ordered index in the cluster, an object is allocated describing what is being indexed and its storage segments. By default, each index so defined also defines an ordered index. Each unique index and primary key has both an ordered index and a hash index. MaxNoOfOrderedIndexes sets the total number of ordered indexes that can be in use in the system at any one time.

    The default value of this parameter is 128. Each index object consumes approximately 10KB of data per node.

    Замечание

    The sum of MaxNoOfTables, MaxNoOfOrderedIndexes, and MaxNoOfUniqueHashIndexes must not exceed 232 – 2 (4294967294).

  • MaxNoOfUniqueHashIndexes

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64
    Range0 .. 4G

    For each unique index that is not a primary key, a special table is allocated that maps the unique key to the primary key of the indexed table. By default, an ordered index is also defined for each unique index. To prevent this, you must specify the USING HASH option when defining the unique index.

    The default value is 64. Each index consumes approximately 15KB per node.

    Замечание

    The sum of MaxNoOfTables, MaxNoOfOrderedIndexes, and MaxNoOfUniqueHashIndexes must not exceed 232 – 2 (4294967294).

  • MaxNoOfTriggers

    Restart Typenode
     Permitted Values
    Typenumeric
    Default768
    Range0 .. 4G

    Internal update, insert, and delete triggers are allocated for each unique hash index. (This means that three triggers are created for each unique hash index.) However, an ordered index requires only a single trigger object. Backups also use three trigger objects for each normal table in the cluster.

    Replication between clusters also makes use of internal triggers.

    This parameter sets the maximum number of trigger objects in the cluster.

    The default value is 768.

  • MaxNoOfIndexes

    This parameter is deprecated in MySQL Cluster 5.5 and later; you should use MaxNoOfOrderedIndexes and MaxNoOfUniqueHashIndexes instead.

    This parameter is used only by unique hash indexes. There needs to be one record in this pool for each unique hash index defined in the cluster.

    The default value of this parameter is 128.

  • MaxNoOfSubscriptions

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    Each NDB table in a MySQL Cluster requires a subscription in the NDB kernel. For some NDB API applications, it may be necessary or desirable to change this paramete. However, for normal usage with MySQL servers acting as SQL nodes, there is not any need to do so.

    The default value for MaxNoOfSubscriptions is 0, which is treated as equal to MaxNoOfTables. Each subscription consumes 108 bytes.

  • MaxNoOfSubscribers

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    This parameter is of interest only when using MySQL Cluster Replication. The default value is 0, which is treated as 2 * MaxNoOfTables; that is, there is one subscription per NDB table for each of two MySQL servers (one acting as the replication master and the other as the slave). Each subscriber uses 16 bytes of memory.

    When using circular replication, multi-master replcation, and other replication setups involving more than 2 MySQL servers, you should increase this parameter to the number of mysqld processes included in replication (this is often, but not always, the same as the number of clusters). For example, if you have a circular replication setup using three MySQL Clusters, with one mysqld attached to each cluster, and each of these mysqld processes acts as a master and as a slave, you should set MaxNoOfSubscribers equal to 3 * MaxNoOfTables.

    For more information, see Section 16.6, “MySQL Cluster Replication”.

  • MaxNoOfConcurrentSubOperations

    Restart Typenode
     Permitted Values
    Typenumeric
    Default256
    Range0 .. 4G
     Permitted Values
    Typenumeric
    Default256
    Range0 .. 4G

    This parameter sets a ceiling on the number of operations that can be performed by all API nodes in the cluster at one time. The default value (256) is sufficient for normal operations, and might need to be adjusted only in scenarios where there are a great many API nodes each performing a high volume of operations concurrently.

Boolean parameters.  The behavior of data nodes is also affected by a set of [ndbd] parameters taking on boolean values. These parameters can each be specified as TRUE by setting them equal to 1 or Y, and as FALSE by setting them equal to 0 or N.

  • LockPagesInMainMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 2

    For a number of operating systems, including Solaris and Linux, it is possible to lock a process into memory and so avoid any swapping to disk. This can be used to help guarantee the cluster's real-time characteristics.

    This parameter takes one of the integer values 0, 1, or 2, which act as shown in the following list:

    • 0: Disables locking. This is the default value.

    • 1: Performs the lock after allocating memory for the process.

    • 2: Performs the lock before memory for the process is allocated.

    If the operating system is not configured to permit unprivileged users to lock pages, then the data node process making use of this parameter may have to be run as system root. (LockPagesInMainMemory uses the mlockall function. From Linux kernel 2.6.9, unprivileged users can lock memory as limited by max locked memory. For more information, see ulimit -l and http://linux.die.net/man/2/mlock).

    Замечание

    In older MySQL Cluster releases, this parameter was a Boolean. 0 or false was the default setting, and disabled locking. 1 or true enabled locking of the process after its memory was allocated. In MySQL Cluster NDB 7.2, using true or false as the value of this parameter causes an error.

  • StopOnError

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaulttrue
    Range ..

    This parameter specifies whether an ndbd process should exit or perform an automatic restart when an error condition is encountered.

    This feature is enabled by default.

  • CrashOnCorruptedTuple

    Version Introduced5.5.16-ndb-7.2.1
    Restart Type 
     Permitted Values
    Typeboolean
    DefaultOFF
     Permitted Values
    Typeboolean
    DefaultON

    When this parameter is enabled, it forces a data node to shut down whenever it encounters a corrupted tuple. In MySQL Cluster NDB 7.2.1 and later, it is enabled by default. This is a change from MySQL Cluster NDB 7.0 and MySQL Cluster NDB 7.1, where it was disabled by default.

  • Diskless

    Restart Typeinitial, system
     Permitted Values
    Typeboolean
    Default0
    Range0 .. 1

    It is possible to specify MySQL Cluster tables as diskless, meaning that tables are not checkpointed to disk and that no logging occurs. Such tables exist only in main memory. A consequence of using diskless tables is that neither the tables nor the records in those tables survive a crash. However, when operating in diskless mode, it is possible to run ndbd on a diskless computer.

    Important

    This feature causes the entire cluster to operate in diskless mode.

    When this feature is enabled, Cluster online backup is disabled. In addition, a partial start of the cluster is not possible.

    Diskless is disabled by default.

  • ODirect

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 1
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 1
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 1

    Enabling this parameter causes NDB to attempt using O_DIRECT writes for LCP, backups, and redo logs, often lowering kswapd and CPU usage. When using MySQL Cluster on Linux, enable ODirect if you are using a 2.6 or later kernel.

    ODirect is disabled by default.

  • RestartOnErrorInsert

    Restart Typenode
     Permitted Values
    Typenumeric
    Default2
    Range0 .. 4

    This feature is accessible only when building the debug version where it is possible to insert errors in the execution of individual blocks of code as part of testing.

    This feature is disabled by default.

  • CompressedBackup

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    Setting this parameter to 1 causes backup files to be compressed. The compression used is equivalent to gzip --fast, and can save 50% or more of the space required on the data node to store uncompressed backup files. Compressed backups can be enabled for individual data nodes, or for all data nodes (by setting this parameter in the [ndbd default] section of the config.ini file).

    Important

    You cannot restore a compressed backup to a cluster running a MySQL version that does not support this feature.

    The default value is 0 (disabled).

  • CompressedLCP

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    Setting this parameter to 1 causes local checkpoint files to be compressed. The compression used is equivalent to gzip --fast, and can save 50% or more of the space required on the data node to store uncompressed checkpoint files. Compressed LCPs can be enabled for individual data nodes, or for all data nodes (by setting this parameter in the [ndbd default] section of the config.ini file).

    Important

    You cannot restore a compressed local checkpoint to a cluster running a MySQL version that does not support this feature.

    The default value is 0 (disabled).

Controlling Timeouts, Intervals, and Disk Paging

There are a number of [ndbd] parameters specifying timeouts and intervals between various actions in Cluster data nodes. Most of the timeout values are specified in milliseconds. Any exceptions to this are mentioned where applicable.

  • TimeBetweenWatchDogCheck

    Restart Typenode
     Permitted Values
    Typenumeric
    Default6000
    Range70 .. 4G

    To prevent the main thread from getting stuck in an endless loop at some point, a “watchdog” thread checks the main thread. This parameter specifies the number of milliseconds between checks. If the process remains in the same state after three checks, the watchdog thread terminates it.

    This parameter can easily be changed for purposes of experimentation or to adapt to local conditions. It can be specified on a per-node basis although there seems to be little reason for doing so.

    The default timeout is 6000 milliseconds (6 seconds).

  • TimeBetweenWatchDogCheckInitial

    Restart Typenode
     Permitted Values
    Typenumeric
    Default6000
    Range70 .. 4G

    This is similar to the TimeBetweenWatchDogCheck parameter, except that TimeBetweenWatchDogCheckInitial controls the amount of time that passes between execution checks inside a database node in the early start phases during which memory is allocated.

    The default timeout is 6000 milliseconds (6 seconds).

  • StartPartialTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default30000
    Range0 .. 4G

    This parameter specifies how long the Cluster waits for all data nodes to come up before the cluster initialization routine is invoked. This timeout is used to avoid a partial Cluster startup whenever possible.

    This parameter is overridden when performing an initial start or initial restart of the cluster.

    The default value is 30000 milliseconds (30 seconds). 0 disables the timeout, in which case the cluster may start only if all nodes are available.

  • StartPartitionedTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default60000
    Range0 .. 4G

    If the cluster is ready to start after waiting for StartPartialTimeout milliseconds but is still possibly in a partitioned state, the cluster waits until this timeout has also passed. If StartPartitionedTimeout is set to 0, the cluster waits indefinitely.

    This parameter is overridden when performing an initial start or initial restart of the cluster.

    The default timeout is 60000 milliseconds (60 seconds).

  • StartFailureTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    If a data node has not completed its startup sequence within the time specified by this parameter, the node startup fails. Setting this parameter to 0 (the default value) means that no data node timeout is applied.

    For nonzero values, this parameter is measured in milliseconds. For data nodes containing extremely large amounts of data, this parameter should be increased. For example, in the case of a data node containing several gigabytes of data, a period as long as 10–15 minutes (that is, 600000 to 1000000 milliseconds) might be required to perform a node restart.

  • StartNoNodeGroupTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default15000
    Range0 .. 4294967039

    When a data node is configured with Nodegroup = 65536, is regarded as not being assigned to any node group. When that is done, the cluster waits StartNoNodegroupTimeout milliseconds, then treats such nodes as though they had been added to the list passed to the --nowait-nodes option, and starts. The default value is 15000 (that is, the management server waits 15 seconds). Setting this parameter equal to 0 means that the cluster waits indefinitely.

    StartNoNodegroupTimeout must be the same for all data nodes in the cluster; for this reason, you should always set it in the [ndbd default] section of the config.ini file, rather than for individual data nodes.

    See Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”, for more information.

  • HeartbeatIntervalDbDb

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1500
    Range10 .. 4G

    One of the primary methods of discovering failed nodes is by the use of heartbeats. This parameter states how often heartbeat signals are sent and how often to expect to receive them. After missing three heartbeat intervals in a row, the node is declared dead. Thus, the maximum time for discovering a failure through the heartbeat mechanism is four times the heartbeat interval.

    In MySQL Cluster NDB 7.2.0 and later, the default heartbeat interval is 5000 milliseconds (5 seconds). (Previously, the default was 1500 milliseconds [1.5 seconds]). This parameter must not be changed drastically and should not vary widely between nodes. If one node uses 5000 milliseconds and the node watching it uses 1000 milliseconds, obviously the node will be declared dead very quickly. This parameter can be changed during an online software upgrade, but only in small increments.

    See also Network communication and latency.

  • HeartbeatIntervalDbApi

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1500
    Range100 .. 4G

    Each data node sends heartbeat signals to each MySQL server (SQL node) to ensure that it remains in contact. If a MySQL server fails to send a heartbeat in time it is declared “dead,” in which case all ongoing transactions are completed and all resources released. The SQL node cannot reconnect until all activities initiated by the previous MySQL instance have been completed. The three-heartbeat criteria for this determination are the same as described for HeartbeatIntervalDbDb.

    The default interval is 1500 milliseconds (1.5 seconds). This interval can vary between individual data nodes because each data node watches the MySQL servers connected to it, independently of all other data nodes.

    For more information, see Network communication and latency.

  • HeartbeatOrder

    Restart Typesystem
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 65535

    Data nodes send heartbeats to one another in a circular fashion whereby each data node monitors the previous one. If a heartbeat is not detected by a given data node, this node declares the previous data node in the circle “dead” (that is, no longer accessible by the cluster). The determination that a data node is dead is done globally; in other words; once a data node is declared dead, it is regarded as such by all nodes in the cluster.

    It is possible for heartbeats between data nodes residing on different hosts to be too slow compared to heartbeats between other pairs of nodes (for example, due to a very low heartbeat interval or temporary connection problem), such that a data node is declared dead, even though the node can still function as part of the cluster. .

    In this type of situation, it may be that the order in which heartbeats are transmitted between data nodes makes a difference as to whether or not a particular data node is declared dead. If this declaration occurs unnecessarily, this can in turn lead to the unnecessary loss of a node group and as thus to a failure of the cluster.

    Consider a setup where there are 4 data nodes A, B, C, and D running on 2 host computers host1 and host2, and that these data nodes make up 2 node groups, as shown in the following table:

     host1host2
    Node Group 0:Node ANode B
    Node Group 1:Node CNode D

    Suppose the heartbeats are transmitted in the order A->B->C->D->A. In this case, the loss of the heartbeat between the hosts causes node B to declare node A dead and node C to declare node B dead. This results in loss of Node Group 0, and so the cluster fails. On the other hand, if the order of transmission is A->B->D->C->A (and all other conditions remain as previously stated), the loss of the heartbeat causes nodes A and D to be declared dead; in this case, each node group has one surviving node, and the cluster survives.

    The HeartbeatOrder configuration parameter makes the order of heartbeat transmission user-configurable. The default value for HeartbeatOrder is zero; allowing the default value to be used on all data nodes causes the order of heartbeat transmission to be determined by NDB. If this parameter is used, it must be set to a nonzero value (maximum 65535) for every data node in the cluster, and this value must be unique for each data node; this causes the heartbeat transmission to proceed from data node to data node in the order of their HeartbeatOrder values from lowest to highest (and then directly from the data node having the highest HeartbeatOrder to the data node having the lowest value, to complete the circle). The values need not be consecutive; for example, to force the heartbeat transmission order A->B->D->C->A in the scenario outlined previously, you could set the HeartbeatOrder values as shown here:

    NodeHeartbeatOrder
    A10
    B20
    C30
    D25

    To use this parameter to change the heartbeat transmission order in a running MySQL Cluster, you must first set HeartbeatOrder for each data node in the cluster in the global configuration (config.ini) file (or files). To cause the change to take effect, you must perform either of the following:

    • A complete shutdown and restart of the entire cluster.

    • 2 rolling restarts of the cluster in succession. All nodes must be restarted in the same order in both rolling restarts.

    You can use DUMP 908 to observe the effect of this parameter in the data node logs.

  • ConnectCheckIntervalDelay

    Restart Typenode
     Permitted Values
    Typestring
    Default1500
    Range0 .. 4G

    This parameter enables connection checking between data nodes. A data node that fails to respond within an interval of ConnectCheckIntervalDelay seconds is considered suspect, and is considered dead after two such intervals.

    The default value for this parameter is 0; this is a change from MySQL Cluster NDB 7.1.

  • TimeBetweenLocalCheckpoints

    Restart Typenode
     Permitted Values
    Typenumeric
    Default20
    Range0 .. 31

    This parameter is an exception in that it does not specify a time to wait before starting a new local checkpoint; rather, it is used to ensure that local checkpoints are not performed in a cluster where relatively few updates are taking place. In most clusters with high update rates, it is likely that a new local checkpoint is started immediately after the previous one has been completed.

    The size of all write operations executed since the start of the previous local checkpoints is added. This parameter is also exceptional in that it is specified as the base-2 logarithm of the number of 4-byte words, so that the default value 20 means 4MB (4 × 220) of write operations, 21 would mean 8MB, and so on up to a maximum value of 31, which equates to 8GB of write operations.

    All the write operations in the cluster are added together. Setting TimeBetweenLocalCheckpoints to 6 or less means that local checkpoints will be executed continuously without pause, independent of the cluster's workload.

  • TimeBetweenGlobalCheckpoints

    Restart Typenode
     Permitted Values
    Typenumeric
    Default2000
    Range10 .. 32000

    When a transaction is committed, it is committed in main memory in all nodes on which the data is mirrored. However, transaction log records are not flushed to disk as part of the commit. The reasoning behind this behavior is that having the transaction safely committed on at least two autonomous host machines should meet reasonable standards for durability.

    It is also important to ensure that even the worst of cases—a complete crash of the cluster—is handled properly. To guarantee that this happens, all transactions taking place within a given interval are put into a global checkpoint, which can be thought of as a set of committed transactions that has been flushed to disk. In other words, as part of the commit process, a transaction is placed in a global checkpoint group. Later, this group's log records are flushed to disk, and then the entire group of transactions is safely committed to disk on all computers in the cluster.

    This parameter defines the interval between global checkpoints. The default is 2000 milliseconds.

  • TimeBetweenEpochs

    Restart Typenode
     Permitted Values
    Typenumeric
    Default100
    Range0 .. 32000

    This parameter defines the interval between synchronisation epochs for MySQL Cluster Replication. The default value is 100 milliseconds.

    TimeBetweenEpochs is part of the implementation of “micro-GCPs”, which can be used to improve the performance of MySQL Cluster Replication.

  • TimeBetweenEpochsTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4000
    Range0 .. 256000

    This parameter defines a timeout for synchronization epochs for MySQL Cluster Replication. If a node fails to participate in a global checkpoint within the time determined by this parameter, the node is shut down. In MySQL Cluster NDB 7.2.0 and later, the default value is 0; in other words, the timeout is disabled. This represents a change from previous versions of MySQL Cluster, in which the default value was 4000 milliseconds (4 seconds).

    TimeBetweenEpochsTimeout is part of the implementation of “micro-GCPs”, which can be used to improve the performance of MySQL Cluster Replication.

    The current value of this parameter and a warning are written to the cluster log whenever a GCP save takes longer than 1 minute or a GCP save takes longer than 10 seconds.

    Setting this parameter to zero has the effect of disabling GCP stops caused by save timeouts, commit timeouts, or both. The maximum possible value for this parameter is 256000 milliseconds.

  • MaxBufferedEpochs

    Restart Typenode
     Permitted Values
    Typenumeric
    Default100
    Range0 .. 100000

    The number of unprocessed epochs by which a subscribing node can lag behind. Exceeding this number causes a lagging subscriber to be disconnected.

    The default value of 100 is sufficient for most normal operations. If a subscribing node does lag enough to cause disconnections, it is usually due to network or scheduling issues with regard to processes or threads. (In rare circumstances, the problem may be due to a bug in the NDB client.) It may be desirable to set the value lower than the default when epochs are longer.

    Disconnection prevents client issues from affecting the data node service, running out of memory to buffer data, and eventually shutting down. Instead, only the client is affected as a result of the disconnect (by, for example gap events in the binary log), forcing the client to reconnect or restart the process.

  • TimeBetweenInactiveTransactionAbortCheck

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1000
    Range1000 .. 4G

    Timeout handling is performed by checking a timer on each transaction once for every interval specified by this parameter. Thus, if this parameter is set to 1000 milliseconds, every transaction will be checked for timing out once per second.

    The default value is 1000 milliseconds (1 second).

  • TransactionInactiveTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4G
    Range0 .. 4G

    This parameter states the maximum time that is permitted to lapse between operations in the same transaction before the transaction is aborted.

    The default for this parameter is 4G (also the maximum). For a real-time database that needs to ensure that no transaction keeps locks for too long, this parameter should be set to a relatively small value. The unit is milliseconds.

  • TransactionDeadlockDetectionTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1200
    Range50 .. 4G

    When a node executes a query involving a transaction, the node waits for the other nodes in the cluster to respond before continuing. A failure to respond can occur for any of the following reasons:

    • The node is “dead

    • The operation has entered a lock queue

    • The node requested to perform the action could be heavily overloaded.

    This timeout parameter states how long the transaction coordinator waits for query execution by another node before aborting the transaction, and is important for both node failure handling and deadlock detection.

    The default timeout value is 1200 milliseconds (1.2 seconds).

    The minimum for this parameter is 50 milliseconds.

  • DiskSyncSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4M
    Range32K .. 4G

    This is the maximum number of bytes to store before flushing data to a local checkpoint file. This is done to prevent write buffering, which can impede performance significantly. This parameter is not intended to take the place of TimeBetweenLocalCheckpoints.

    Замечание

    When ODirect is enabled, it is not necessary to set DiskSyncSize; in fact, in such cases its value is simply ignored.

    The default value is 4M (4 megabytes).

  • DiskCheckpointSpeed

    Restart Typenode
     Permitted Values
    Typenumeric
    Default10M
    Range1M .. 4G

    The amount of data,in bytes per second, that is sent to disk during a local checkpoint. This allocation is shared by DML operations and backups (but not backup logging), which means that backups started during times of intensive DML may be impaired by flooding of the redo log buffer and may fail altogether if the contention is sufficiently severe.

    The default value is 10M (10 megabytes per second).

  • DiskCheckpointSpeedInRestart

    Restart Typenode
     Permitted Values
    Typenumeric
    Default100M
    Range1M .. 4G

    The amount of data,in bytes per second, that is sent to disk during a local checkpoint as part of a restart operation.

    The default value is 100M (100 megabytes per second).

  • NoOfDiskPagesToDiskAfterRestartTUP

    Restart Typenode
     Permitted Values
    Typenumeric
    Default40
    Range1 .. 4G

    When executing a local checkpoint, the algorithm flushes all data pages to disk. Merely doing so as quickly as possible without any moderation is likely to impose excessive loads on processors, networks, and disks. To control the write speed, this parameter specifies how many pages per 100 milliseconds are to be written. In this context, a “page” is defined as 8KB. This parameter is specified in units of 80KB per second, so setting NoOfDiskPagesToDiskAfterRestartTUP to a value of 20 entails writing 1.6MB in data pages to disk each second during a local checkpoint. This value includes the writing of UNDO log records for data pages. That is, this parameter handles the limitation of writes from data memory. (See the entry for IndexMemory for information about index pages.)

    In short, this parameter specifies how quickly to execute local checkpoints. It operates in conjunction with NoOfFragmentLogFiles, DataMemory, and IndexMemory.

    For more information about the interaction between these parameters and possible strategies for choosing appropriate values for them, see Configuring MySQL Cluster Parameters for Local Checkpoints.

    The default value is 40 (3.2MB of data pages per second).

    Замечание

    This parameter is deprecated. Use DiskCheckpointSpeedInRestart and DiskSyncSize instead.

  • NoOfDiskPagesToDiskAfterRestartACC

    Restart Typenode
     Permitted Values
    Typenumeric
    Default20
    Range1 .. 4G

    This parameter uses the same units as NoOfDiskPagesToDiskAfterRestartTUP and acts in a similar fashion, but limits the speed of writing index pages from index memory.

    The default value of this parameter is 20 (1.6MB of index memory pages per second).

    Замечание

    This parameter is deprecated. Use DiskCheckpointSpeedInRestart and DiskSyncSize instead.

  • NoOfDiskPagesToDiskDuringRestartTUP (DEPRECATED)

    Restart Typenode
     Permitted Values
    Typenumeric
    Default40
    Range1 .. 4G

    This parameter is used in a fashion similar to NoOfDiskPagesToDiskAfterRestartTUP and NoOfDiskPagesToDiskAfterRestartACC, only it does so with regard to local checkpoints executed in the node when a node is restarting. A local checkpoint is always performed as part of all node restarts. During a node restart it is possible to write to disk at a higher speed than at other times, because fewer activities are being performed in the node.

    This parameter covers pages written from data memory.

    The default value is 40 (3.2MB per second).

    Замечание

    This parameter is deprecated. Use DiskCheckpointSpeedInRestart and DiskSyncSize instead.

  • NoOfDiskPagesToDiskDuringRestartACC (DEPRECATED)

    Restart Typenode
     Permitted Values
    Typenumeric
    Default20
    Range1 .. 4G

    Controls the number of index memory pages that can be written to disk during the local checkpoint phase of a node restart.

    As with NoOfDiskPagesToDiskAfterRestartTUP and NoOfDiskPagesToDiskAfterRestartACC, values for this parameter are expressed in terms of 8KB pages written per 100 milliseconds (80KB/second).

    The default value is 20 (1.6MB per second).

    Замечание

    This parameter is deprecated. Use DiskCheckpointSpeedInRestart and DiskSyncSize instead.

  • ArbitrationTimeout

    Restart Typenode
     Permitted Values
    Typenumeric
    Default3000
    Range10 .. 4G

    This parameter specifies how long data nodes wait for a response from the arbitrator to an arbitration message. If this is exceeded, the network is assumed to have split.

    In MySQL Cluster NDB 7.2.0 and later, the default value is 7500 milliseconds (7.5 seconds). Previously, this was 3000 milliseconds (3 seconds).

  • Arbitration

    Restart Typenode
     Permitted Values
    Typeenumeration
    DefaultDefault
    Valid Values

    Default

    Disabled

    WaitExternal

    The Arbitration parameter enables a choice of arbitration schemes, corresponding to one of 3 possible values for this parameter:

    • Default This enables arbitration to proceed normally, as determined by the ArbitrationRank settings for the management and API nodes. This is the default value.

    • Disabled Setting Arbitration = Disabled in the [ndbd default] section of the config.ini file to accomplishes the same task as setting ArbitrationRank to 0 on all management and API nodes. When Arbitration is set in this way, any ArbitrationRank settings are ignored.

    • WaitExternal The Arbitration parameter also makes it possible to configure arbitration in such a way that the cluster waits until after the time determined by ArbitrationTimeout has passed for an external cluster manager application to perform arbitration instead of handling arbitration internally. This can be done by setting Arbitration = WaitExternal in the [ndbd default] section of the config.ini file. For best results with the WaitExternal setting, it is recommended that ArbitrationTimeout be 2 times as long as the interval required by the external cluster manager to perform arbitration.

    Important

    This parameter should be used only in the [ndbd default] section of the cluster configuration file. The behavior of the cluster is unspecified when Arbitration is set to different values for individual data nodes.

Buffering and logging.  Several [ndbd] configuration parameters enable the advanced user to have more control over the resources used by node processes and to adjust various buffer sizes at need.

These buffers are used as front ends to the file system when writing log records to disk. If the node is running in diskless mode, these parameters can be set to their minimum values without penalty due to the fact that disk writes are “faked” by the NDB storage engine's file system abstraction layer.

  • UndoIndexBuffer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default2M
    Range1M .. 4G

    The UNDO index buffer, whose size is set by this parameter, is used during local checkpoints. The NDB storage engine uses a recovery scheme based on checkpoint consistency in conjunction with an operational REDO log. To produce a consistent checkpoint without blocking the entire system for writes, UNDO logging is done while performing the local checkpoint. UNDO logging is activated on a single table fragment at a time. This optimization is possible because tables are stored entirely in main memory.

    The UNDO index buffer is used for the updates on the primary key hash index. Inserts and deletes rearrange the hash index; the NDB storage engine writes UNDO log records that map all physical changes to an index page so that they can be undone at system restart. It also logs all active insert operations for each fragment at the start of a local checkpoint.

    Reads and updates set lock bits and update a header in the hash index entry. These changes are handled by the page-writing algorithm to ensure that these operations need no UNDO logging.

    This buffer is 2MB by default. The minimum value is 1MB, which is sufficient for most applications. For applications doing extremely large or numerous inserts and deletes together with large transactions and large primary keys, it may be necessary to increase the size of this buffer. If this buffer is too small, the NDB storage engine issues internal error code 677 (Index UNDO buffers overloaded).

    Important

    It is not safe to decrease the value of this parameter during a rolling restart.

  • UndoDataBuffer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default16M
    Range1M .. 4G

    This parameter sets the size of the UNDO data buffer, which performs a function similar to that of the UNDO index buffer, except the UNDO data buffer is used with regard to data memory rather than index memory. This buffer is used during the local checkpoint phase of a fragment for inserts, deletes, and updates.

    Because UNDO log entries tend to grow larger as more operations are logged, this buffer is also larger than its index memory counterpart, with a default value of 16MB.

    This amount of memory may be unnecessarily large for some applications. In such cases, it is possible to decrease this size to a minimum of 1MB.

    It is rarely necessary to increase the size of this buffer. If there is such a need, it is a good idea to check whether the disks can actually handle the load caused by database update activity. A lack of sufficient disk space cannot be overcome by increasing the size of this buffer.

    If this buffer is too small and gets congested, the NDB storage engine issues internal error code 891 (Data UNDO buffers overloaded).

    Important

    It is not safe to decrease the value of this parameter during a rolling restart.

  • RedoBuffer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default8M
    Range1M .. 4G

    All update activities also need to be logged. The REDO log makes it possible to replay these updates whenever the system is restarted. The NDB recovery algorithm uses a “fuzzy” checkpoint of the data together with the UNDO log, and then applies the REDO log to play back all changes up to the restoration point.

    RedoBuffer sets the size of the buffer in which the REDO log is written. The default value is 32MB; the minimum value is 1MB.

    If this buffer is too small, the NDB storage engine issues error code 1221 (REDO log buffers overloaded). For this reason, you should exercise care if you attempt to decrease the value of RedoBuffer as part of an online change in the cluster's configuration.

Controlling log messages.  In managing the cluster, it is very important to be able to control the number of log messages sent for various event types to stdout. For each event category, there are 16 possible event levels (numbered 0 through 15). Setting event reporting for a given event category to level 15 means all event reports in that category are sent to stdout; setting it to 0 means that there will be no event reports made in that category.

By default, only the startup message is sent to stdout, with the remaining event reporting level defaults being set to 0. The reason for this is that these messages are also sent to the management server's cluster log.

An analogous set of levels can be set for the management client to determine which event levels to record in the cluster log.

  • LogLevelStartup

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1
    Range0 .. 15

    The reporting level for events generated during startup of the process.

    The default level is 1.

  • LogLevelShutdown

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated as part of graceful shutdown of a node.

    The default level is 0.

  • LogLevelStatistic

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for statistical events such as number of primary key reads, number of updates, number of inserts, information relating to buffer usage, and so on.

    The default level is 0.

  • LogLevelCheckpoint

    Restart Typeinitial, node
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated by local and global checkpoints.

    The default level is 0.

  • LogLevelNodeRestart

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated during node restart.

    The default level is 0.

  • LogLevelConnection

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated by connections between cluster nodes.

    The default level is 0.

  • LogLevelError

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated by errors and warnings by the cluster as a whole. These errors do not cause any node failure but are still considered worth reporting.

    The default level is 0.

  • LogLevelCongestion

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated by congestion. These errors do not cause node failure but are still considered worth reporting.

    The default level is 0.

  • LogLevelInfo

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 15

    The reporting level for events generated for information about the general state of the cluster.

    The default level is 0.

  • MemReportFrequency

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    This parameter controls how often data node memory usage reports are recorded in the cluster log; it is an integer value representing the number of seconds between reports.

    Each data node's data memory and index memory usage is logged as both a percentage and a number of 32 KB pages of the DataMemory and IndexMemory, respectively, set in the config.ini file. For example, if DataMemory is equal to 100 MB, and a given data node is using 50 MB for data memory storage, the corresponding line in the cluster log might look like this:

    2006-12-24 01:18:16 [MgmSrvr] INFO -- Node 2: Data usage is 50%(1280 32K pages of total 2560)

    MemReportFrequency is not a required parameter. If used, it can be set for all cluster data nodes in the [ndbd default] section of config.ini, and can also be set or overridden for individual data nodes in the corresponding [ndbd] sections of the configuration file. The minimum value—which is also the default value—is 0, in which case memory reports are logged only when memory usage reaches certain percentages (80%, 90%, and 100%), as mentioned in the discussion of statistics events in Section 16.5.5.2, “MySQL Cluster Log Events”.

  • StartupStatusReportFrequency

    Restart Typenode
     Permitted Values
    Typenumeric

    When a data node is started with the --initial, it initializes the redo log file during Start Phase 4 (see Section 16.5.1, “Summary of MySQL Cluster Start Phases”). When very large values are set for NoOfFragmentLogFiles, FragmentLogFileSize, or both, this initialization can take a long time.You can force reports on the progress of this process to be logged periodically, by means of the StartupStatusReportFrequency configuration parameter. In this case, progress is reported in the cluster log, in terms of both the number of files and the amount of space that have been initialized, as shown here:

    2009-06-20 16:39:23 [MgmSrvr] INFO -- Node 1: Local redo log file initialization status:
    #Total files: 80, Completed: 60
    #Total MBytes: 20480, Completed: 15557
    2009-06-20 16:39:23 [MgmSrvr] INFO -- Node 2: Local redo log file initialization status:
    #Total files: 80, Completed: 60
    #Total MBytes: 20480, Completed: 15570

    These reports are logged each StartupStatusReportFrequency seconds during Start Pahe 4. If StartupStatusReportFrequency is 0 (the default), then reports are written to the cluster log only when at the beginning and at the completion of the redo log file initialization process.

Debugging Parameters.  In MySQL Cluster NDB 7.2, it is possible to cause logging of traces for events generated by creating and dropping tables using DictTrace. This parameter is useful only in debugging NDB kernel code. DictTrace takes an integer value; currently, 0 (default - no logging) and 1 (logging enabled) are the only supported values.

Backup parameters.  The [ndbd] parameters discussed in this section define memory buffers set aside for execution of online backups.

  • BackupDataBufferSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default2M
    Range0 .. 4G

    In creating a backup, there are two buffers used for sending data to the disk. The backup data buffer is used to fill in data recorded by scanning a node's tables. Once this buffer has been filled to the level specified as BackupWriteSize, the pages are sent to disk. While flushing data to disk, the backup process can continue filling this buffer until it runs out of space. When this happens, the backup process pauses the scan and waits until some disk writes have completed freed up memory so that scanning may continue.

    The default value for this parameter is 16MB.

  • BackupLogBufferSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default2M
    Range0 .. 4G

    The backup log buffer fulfills a role similar to that played by the backup data buffer, except that it is used for generating a log of all table writes made during execution of the backup. The same principles apply for writing these pages as with the backup data buffer, except that when there is no more space in the backup log buffer, the backup fails. For that reason, the size of the backup log buffer must be large enough to handle the load caused by write activities while the backup is being made. See Section 16.5.3.3, “Configuration for MySQL Cluster Backups”.

    The default value for this parameter should be sufficient for most applications. In fact, it is more likely for a backup failure to be caused by insufficient disk write speed than it is for the backup log buffer to become full. If the disk subsystem is not configured for the write load caused by applications, the cluster is unlikely to be able to perform the desired operations.

    It is preferable to configure cluster nodes in such a manner that the processor becomes the bottleneck rather than the disks or the network connections.

    The default value for this parameter is 16MB.

  • BackupMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default4M
    Range0 .. 4G

    This parameter is simply the sum of BackupDataBufferSize and BackupLogBufferSize.

    The default valueof this parameter in MySQL Cluster NDB 7.2 is 16MB + 16MB = 32MB.

    Important

    If BackupDataBufferSize and BackupLogBufferSize taken together exceed the default value for BackupMemory, then this parameter must be set explicitly in the config.ini file to their sum.

  • BackupReportFrequency

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    This parameter controls how often backup status reports are issued in the management client during a backup, as well as how often such reports are written to the cluster log (provided cluster event logging is configured to permit it—see Logging and checkpointing). BackupReportFrequency represents the time in seconds between backup status reports.

    The default value is 0.

  • BackupWriteSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default32K
    Range2K .. 4G

    This parameter specifies the default size of messages written to disk by the backup log and backup data buffers.

    The default value for this parameter is 256KB.

  • BackupMaxWriteSize

    Restart Typenode
     Permitted Values (>= 5.5)
    Typenumeric
    Default1M
    Range2K .. 4G

    This parameter specifies the maximum size of messages written to disk by the backup log and backup data buffers.

    The default value for this parameter is 1MB.

Important

When specifying these parameters, the following relationships must hold true. Otherwise, the data node will be unable to start.

  • BackupDataBufferSize >= BackupWriteSize + 188KB

  • BackupLogBufferSize >= BackupWriteSize + 16KB

  • BackupMaxWriteSize >= BackupWriteSize

MySQL Cluster Realtime Performance Parameters

The [ndbd] parameters discussed in this section are used in scheduling and locking of threads to specific CPUs on multiprocessor data node hosts.

Замечание

To make use of these parameters, the data node process must be run as system root.

  • LockExecuteThreadToCPU

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64K
    Range0 .. 64K

    When used with ndbd, this parameter (now a string) specifies the ID of the CPU assigned to handle the NDBCLUSTER execution thread. When used with ndbmtd, the value of this parameter is a comma-separated list of CPU IDs assigned to handle execution threads. Each CPU ID in the list should be an integer in the range 0 to 65535 (inclusive).

    The number of IDs specified should match the number of execution threads determined by MaxNoOfExecutionThreads. However, there is no guarantee that threads are assigned to CPUs in any given order when using this parameter; beginning with in MySQL Cluster NDB 7.2.5, you can obtain more finely-grained control of this type using ThreadConfig.

    LockExecuteThreadToCPU has no default value.

  • LockMaintThreadsToCPU

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64K
    Range0 .. 64K

    This parameter specifies the ID of the CPU assigned to handle NDBCLUSTER maintenance threads.

    The value of this parameter is an integer in the range 0 to 65535 (inclusive). In MySQL Cluster NDB 7.2, there is no default value.

  • RealtimeScheduler

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    Setting this parameter to 1 enables real-time scheduling of NDBCLUSTER threads.

    The default is 0 (scheduling disabled).

  • SchedulerExecutionTimer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default50
    Range0 .. 11000

    This parameter specifies the time in microseconds for threads to be executed in the scheduler before being sent. Setting it to 0 minimizes the response time; to achieve higher throughput, you can increase the value at the expense of longer response times.

    The default is 50 μsec, which our testing shows to increase throughput slightly in high-load cases without materially delaying requests.

  • SchedulerSpinTimer

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 500

    This parameter specifies the time in microseconds for threads to be executed in the scheduler before sleeping.

    The default value is 0.

  • BuildIndexThreads

    Restart Type 
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 128

    This parameter determines the number of threads to create when rebuilding indexes during a system or node start. It is supported only when there is more than one fragment for the table per data node (for example, when the MAX_ROWS option has been used with CREATE TABLE).

    Setting this parameter to 0 (which is also the default value) disables multi-threaded building of ordered indexes. The maximum allowed value is 128.

    This parameter is supported when using ndbd or ndbmtd.

    You can enable multi-threaded builds during data node initial restarts by setting the TwoPassInitialNodeRestartCopy data node configuration parameter to TRUE.

  • TwoPassInitialNodeRestartCopy

    Multi-threaded building of ordered indexes can be enabled for initial restarts of data nodes by setting this configuration parameter to TRUE, which enables two-pass copying of data during initial node restarts.

    You must also set BuildIndexThreads to a nonzero value.

  • ThreadConfig

    Version Introduced5.5.17-ndb-7.2.3
    Restart Typenode
     Permitted Values
    Typestring
    Default[none]

    This parameter is used with ndbmtd to assign threads of different types to different CPUs. Its value is a string whose format has the following syntax:

    ThreadConfig := entry[,entry[,...]]
    
    entry := type={param[,param[,...]]}
    
    type := ldm | main | recv | rep | io
    
    param := count=number | cpubind=cpu_list
    

    The curly braces ({...}) surrounding the list of parameters is required, even if there is only one parameter in the list.

    The type attribute represents an NDB thread type. Permitted values and their associated thread types are described in the following list:

    • ldm: Local query handler (DBLQH kernel block)

    • main: Data dictionary and transaction coordinator (DBDIH and DBTC kernel blocks)

    • recv: NDB kernel virtual machine (CMVMI kernel block)

    • rep: SUMA kernel block

    • io: File system and other miscellaneous operations

    A param (parameter) specifies the number of threads of the given type (count), the CPUs to which the threads of the given type are to be bound (cpubind), or both.

    Examples:

    # Пример 1.
    
    ThreadConfig=ldm={count=2,cpubind=1,2},main={cpubind=12},rep={cpubind=11}
    
    # Пример 2.
    
    Threadconfig=main={cpubind=0},ldm={count=4,cpubind=1,2,5,6},io={count=2,cpubind=3,4}

Numa

Restart Typenode
 Permitted Values
Type (linux)boolean
Default0

NDB is extremely sensitive to Non-Uniform Memory Access settings and multi-CPU systems due to timeouts that it can cause. Due to this fact, and because most MySQL Cluster users do not employ numactl, support for NUMA is ignored by default by ndbd when running on a Linux system. If your Linux system provides NUMA support and you wish for data node memory to be subject to NUMA control, you can set this parameter equal to 0.

The Numa configuration parameter is supported only on Linux systems where libnuma.so is installed.

Disk Data Configuration Parameters.  Configuration parameters affecting Disk Data behavior include the following:

  • DiskPageBufferMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64M
    Range4M .. 1T

    This determines the amount of space used for caching pages on disk, and is set in the [ndbd] or [ndbd default] section of the config.ini file. It is measured in bytes. Each page takes up 32 KB. This means that Cluster Disk Data storage always uses N * 32 KB memory where N is some nonnegative integer.

    The default value for this parameter is 64M (2000 pages of 32 KB each).

    You can query the ndbinfo.diskpagebuffer table to help determine whether the value for this parameter should be increased to minimize unnecessary disk seeks. See Section 16.5.9.4, “The ndbinfo diskpagebuffer Table”, for more information.

  • SharedGlobalMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default20M
    Range0 .. 64T

    This parameter determines the amount of memory that is used for log buffers, disk operations (such as page requests and wait queues), and metadata for tablespaces, log file groups, UNDO files, and data files. The shared global memory pool also provides memory used for satisfying the memory requirements of the INITIAL_SIZE and UNDO_BUFFER_SIZE options used with CREATE LOGFILE GROUP and ALTER LOGFILE GROUP statements, including any default value implied for these options by the setting of the InitialLogFileGroup data node configuration parameter. SharedGlobalMemory can be set in the [ndbd] or [ndbd default] section of the config.ini configuration file, and is measured in bytes.

    As of MySQL Cluster NDB 7.2.0, the default value is 128M. (Previously, this was 20M.)

  • DiskIOThreadPool

    Restart Typenode
     Permitted Values
    Typenumeric
    Default8
    Range0 .. 4G
     Permitted Values
    Typenumeric
    Default2
    Range0 .. 4G
     Permitted Values
    Typenumeric
    Default2
    Range0 .. 4G

    This parameter determines the number of unbound threads used for Disk Data file access. Before DiskIOThreadPool was introduced, exactly one thread was spawned for each Disk Data file, which could lead to performance issues, particularly when using very large data files. With DiskIOThreadPool, you can—for example—access a single large data file using several threads working in parallel.

    Currently, this parameter applies to Disk Data I/O threads only, but we plan in the future to make the number of such threads configurable for in-memory data as well.

    The optimum value for this parameter depends on your hardware and configuration, and includes these factors:

    • Physical distribution of Disk Data files.  You can obtain better performance by placing data files, undo log files, and the data node file system on separate physical disks. If you do this with some or all of these sets of files, then you can set DiskIOThreadPool higher to enable separate threads to handle the files on each disk.

    • Disk performance and types.  The number of threads that can be accommodated for Disk Data file handling is also dependent on the speed and throughput of the disks. Faster disks and higher throughput allow for more disk I/O threads. Our test results indicate that solid-state disk drives can handle many more disk I/O threads than conventional disks, and thus higher values for DiskIOThreadPool.

    In MySQL Cluster NDB 7.2, the default value for this parameter is 2.

  • Disk Data file system parameters.  The parameters in the following list make it possible to place MySQL Cluster Disk Data files in specific directories without the need for using symbolic links.

    • FileSystemPathDD

      Restart Typeinitial, node
       Permitted Values
      Typefile name
      DefaultFileSystemPath
      Range ..

      If this parameter is specified, then MySQL Cluster Disk Data data files and undo log files are placed in the indicated directory. This can be overridden for data files, undo log files, or both, by specifying values for FileSystemPathDataFiles, FileSystemPathUndoFiles, or both, as explained for these parameters. It can also be overridden for data files by specifying a path in the ADD DATAFILE clause of a CREATE TABLESPACE or ALTER TABLESPACE statement, and for undo log files by specifying a path in the ADD UNDOFILE clause of a CREATE LOGFILE GROUP or ALTER LOGFILE GROUP statement. If FileSystemPathDD is not specified, then FileSystemPath is used.

      If a FileSystemPathDD directory is specified for a given data node (including the case where the parameter is specified in the [ndbd default] section of the config.ini file), then starting that data node with --initial causes all files in the directory to be deleted.

    • FileSystemPathDataFiles

      Restart Typeinitial, node
       Permitted Values
      Typefile name
      DefaultFileSystemPathDD
      Range ..

      If this parameter is specified, then MySQL Cluster Disk Data data files are placed in the indicated directory. This overrides any value set for FileSystemPathDD. This parameter can be overridden for a given data file by specifying a path in the ADD DATAFILE clause of a CREATE TABLESPACE or ALTER TABLESPACE statement used to create that data file. If FileSystemPathDataFiles is not specified, then FileSystemPathDD is used (or FileSystemPath, if FileSystemPathDD has also not been set).

      If a FileSystemPathDataFiles directory is specified for a given data node (including the case where the parameter is specified in the [ndbd default] section of the config.ini file), then starting that data node with --initial causes all files in the directory to be deleted.

    • FileSystemPathUndoFiles

      Restart Typeinitial, node
       Permitted Values
      Typefile name
      DefaultFileSystemPathDD
      Range ..

      If this parameter is specified, then MySQL Cluster Disk Data undo log files are placed in the indicated directory. This overrides any value set for FileSystemPathDD. This parameter can be overridden for a given data file by specifying a path in the ADD UNDO clause of a CREATE LOGFILE GROUP or CREATE LOGFILE GROUP statement used to create that data file. If FileSystemPathUndoFiles is not specified, then FileSystemPathDD is used (or FileSystemPath, if FileSystemPathDD has also not been set).

      If a FileSystemPathUndoFiles directory is specified for a given data node (including the case where the parameter is specified in the [ndbd default] section of the config.ini file), then starting that data node with --initial causes all files in the directory to be deleted.

    For more information, see Section 16.5.11.1, “MySQL Cluster Disk Data Objects”.

  • Disk Data object creation parameters.  The next two parameters enable you—when starting the cluster for the first time—to cause a Disk Data log file group, tablespace, or both, to be created without the use of SQL statements.

    • InitialLogFileGroup

      Restart Typesystem
       Permitted Values
      Typestring
      Default[see documentation]
      Range ..

      This parameter can be used to specify a log file group that is created when performing an initial start of the cluster. InitialLogFileGroup is specified as shown here:

      InitialLogFileGroup = [name=name;] [undo_buffer_size=size;] file-specification-list
      
      file-specification-list:
          file-specification[; file-specification[; ...]]
      
      file-specification:
          filename:size
      

      The name of the log file group is optional and defaults to DEFAULT-LG. The undo_buffer_size is also optional; if omitted, it defaults to 64M. Each file-specification corresponds to an undo log file, and at least one must be specified in the file-specification-list. Undo log files are placed according to any values that have been set for FileSystemPath, FileSystemPathDD, and FileSystemPathUndoFiles, just as if they had been created as the result of a CREATE LOGFILE GROUP or ALTER LOGFILE GROUP statement.

      Consider the following:

      InitialLogFileGroup = name=LG1; undo_buffer_size=128M; undo1.log:250M; undo2.log:150M

      This is equivalent to the following SQL statements:

      CREATE LOGFILE GROUP LG1
          ADD UNDOFILE 'undo1.log'
          INITIAL_SIZE 250M
          UNDO_BUFFER_SIZE 128M
          ENGINE NDBCLUSTER;
      
      ALTER LOGFILE GROUP LG1
          ADD UNDOFILE 'undo2.log'
          INITIAL_SIZE 150M
          ENGINE NDBCLUSTER;

      This logfile group is created when the data nodes are started with --initial.

      Resources for the initial log file group are taken from the global memory pool whose size is determined by the value of the SharedGlobalMemory data node configuration parameter; if this parameter is set too low and the values set in InitialLogFileGroup for the logfile group's initial size or undo buffer size are too high, the cluster may fail to create the default log file group when starting, or fail to start altogether.

      This parameter, if used, should always be set in the [ndbd default] section of the config.ini file. The behavior of a MySQL Cluster when different values are set on different data nodes is not defined.

    • InitialTablespace

      Restart Typesystem
       Permitted Values
      Typestring
      Default[see documentation]
      Range ..

      This parameter can be used to specify a MySQL Cluster Disk Data tablespace that is created when performing an initial start of the cluster. InitialTablespace is specified as shown here:

      InitialTablespace = [name=name;] [extent_size=size;] file-specification-list
      

      The name of the tablespace is optional and defaults to DEFAULT-TS. The extent_size is also optional; it defaults to 1M. The file-specification-list uses the same syntax as shown with the InitialLogfileGroup parameter, the only difference being that each file-specification used with InitialTablespace corresponds to a data file. At least one must be specified in the file-specification-list. Data files are placed according to any values that have been set for FileSystemPath, FileSystemPathDD, and FileSystemPathDataFiles, just as if they had been created as the result of a CREATE TABLESPACE or ALTER TABLESPACE statement.

      For example, consider the following line specifying InitialTablespace in the [ndbd default] section of the config.ini file (as with InitialLogfileGroup, this parameter should always be set in the [ndbd default] section, as the behavior of a MySQL Cluster when different values are set on different data nodes is not defined):

      InitialTablespace = name=TS1; extent_size=8M; data1.dat:2G; data2.dat:4G

      This is equivalent to the following SQL statements:

      CREATE TABLESPACE TS1
          ADD DATAFILE 'data1.dat'
          EXTENT_SIZE 8M
          INITIAL_SIZE 2G
          ENGINE NDBCLUSTER;
      
      ALTER TABLESPACE TS1
          ADD UNDOFILE 'data2.dat'
          INITIAL_SIZE 4G
          ENGINE NDBCLUSTER;

      This tablespace is created when the data nodes are started with --initial, and can be used whenever creating MySQL Cluster Disk Data tables thereafter.

Disk Data and GCP Stop errors.  Ошибки encountered when using Disk Data tables such as Node nodeid killed this node because GCP stop was detected (error 2303) are often referred to as “GCP stop errors”. Such errors occur when the redo log is not flushed to disk quickly enough; this is usually due to slow disks and insufficient disk throughput.

You can help prevent these errors from occurring by using faster disks, and by placing Disk Data files on a separate disk from the data node file system. Reducing the value of TimeBetweenGlobalCheckpoints tends to decrease the amount of data to be written for each global checkpoint, and so may provide some protection against redo log buffer overflows when trying to write a global checkpoint; however, reducing this value also permits less time in which to write the GCP, so this must be done with caution.

In addition to the considerations given for DiskPageBufferMemory as explained previously, it is also very important that the DiskIOThreadPool configuration parameter be set correctly; having DiskIOThreadPool set too high is very likely to cause GCP stop errors (Bug #37227).

GCP stops can be caused by save or commit timeouts; the TimeBetweenEpochsTimeout data node configuration parameter determines the timeout for commits. However, it is possible to disable both types of timeouts by setting this parameter to 0.

Parameters for configuring send buffer memory allocation.  Send buffer memory is allocated dynamically from a memory pool shared between all transporters, which means that the size of the send buffer can be adjusted as necessary. (Previously, the NDB kernel used a fixed-size send buffer for every node in the cluster, which was allocated when the node started and could not be changed while the node was running.) The TotalSendBufferMemory and OverLoadLimit data node configuration parameters permit the setting of limits on this memory allocation. For more information about the use of these parameters (as well as SendBufferMemory), see Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”.

  • ExtraSendBufferMemory

    This parameter specifies the amount of transporter send buffer memory to allocate in addition to any set using TotalSendBufferMemory, SendBufferMemory, or both.

    This parameter was added in MySQL Cluster NDB 7.2.5. (Bug #11760629, Bug #53053)

  • TotalSendBufferMemory

    This parameter is available beginning with MySQL Cluster NDB 6.4.0. It is used to determine the total amount of memory to allocate on this node for shared send buffer memory among all configured transporters.

    Prior to MySQL Cluster NDB 7.2.5, this parameter did not work correctly with ndbmtd. (Bug #13633845)

    If this parameter is set, its minimum permitted value is 256KB; the maxmimum is 4294967039.

  • ReservedSendBufferMemory

    This parameter is present in NDBCLUSTER source code beginning with MySQL Cluster NDB 6.4.0. However, it is not currently enabled.

    As of MySQL Cluster NDB 7.2.5, this parameter is deprecated, and is subject to removal in a future release of MySQL Cluster (Bug #11760629, Bug #53053).

For more detailed information about the behavior and use of TotalSendBufferMemory and about configuring send buffer memory parameters in MySQL Cluster, see Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”.

See also Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”.

Redo log over-commit handling.  It is possible to control a data node's handling of operations when too much time is taken flushing redo logs to disk. This occurs when a given redo log flush takes longer than RedoOverCommitLimit seconds, more than RedoOverCommitCounter times, causing any pending transactions to be aborted. When this happens, the API node that sent the transaction can handle the operations that should have been committed either by queuing the operations and re-trying them, or by aborting them, as determined by DefaultOperationRedoProblemAction. The data node configuration parameters for setting the timeout and number of times it may be exceeded before the API node takes this action are described in the following list:

  • RedoOverCommitCounter

    Restart Typenode
     Permitted Values
    Typenumeric
    Default3
    Range0 .. 4G

    When RedoOverCommitLimit is exceeded when trying to write a given redo log to disk this many times or more, any transactions that were not committed as a result are aborted, and an API node where any of these transactions originated handles the operations making up those transactions according to its value for DefaultOperationRedoProblemAction (by either queuing the operations to be re-tried, or aborting them).

    RedoOverCommitCounter defaults to 3. Set it to 0 to disable the limit.

  • RedoOverCommitLimit

    Restart Typenode
     Permitted Values
    Typenumeric
    Default20
    Range0 .. 4G

    This parameter sets an upper limit in seconds for trying to write a given redo log to disk before timing out. The number of times the data node tries to flush this redo log, but takes longer than RedoOverCommitLimit, is kept and compared with RedoOverCommitCounter, and when flushing takes too long more times than the value of that parameter, any transactions that were not committed as a result of the flush timeout are aborted. When this occurs, the API node where any of these transactions originated handles the operations making up those transactions according to its DefaultOperationRedoProblemAction setting (it either queues the operations to be re-tried, or aborts them).

    By default, RedoOverCommitLimit is 20 seconds. Set to 0 to disable checking for redo log flush timeouts. This parameter was added in MySQL Cluster NDB 7.1.10.

Controlling restart attempts.  It is possible to exercise finely-grained control over restart attempts by data nodes when they fail to start using the MaxStartFailRetries and StartFailRetryDelay data node configuration parameters.

MaxStartFailRetries limits the total number of retries made before giving up on starting the data node, StartFailRetryDelay sets the number of seconds between retry attempts. These parameters are described in more detail in the next few paragraphs.

StartFailRetryDelay

Restart Typenode
 Permitted Values
Typenumeric
Default0
Range0 .. 4G
 Permitted Values
Typenumeric
Default0
Range0 .. 4G
 Permitted Values
Typenumeric
Default0
Range0 .. 4G
 Permitted Values
Typenumeric
Default0
Range0 .. 4G

Use this parameter to set the number of seconds between restart attempts by the data node in the event on failure on startup. The default is 0 (no delay).

Замечание

This parameter is ignored unless StartOnError is equal to 0.

MaxStartFailRetries

Restart Typenode
 Permitted Values
Typenumeric
Default3
Range0 .. 4G
 Permitted Values
Typenumeric
Default3
Range0 .. 4G
 Permitted Values
Typenumeric
Default3
Range0 .. 4G
 Permitted Values
Typenumeric
Default3
Range0 .. 4G

Use this parameter to limit the number restart attempts made by the data node in the event that it fails on startup. The default is 3 attempts.

Замечание

This parameter is ignored unless StopOnError is equal to 0.

16.3.2.7. Defining SQL and Other API Nodes in a MySQL Cluster

The [mysqld] and [api] sections in the config.ini file define the behavior of the MySQL servers (SQL nodes) and other applications (API nodes) used to access cluster data. None of the parameters shown is required. If no computer or host name is provided, any host can use this SQL or API node.

Generally speaking, a [mysqld] section is used to indicate a MySQL server providing an SQL interface to the cluster, and an [api] section is used for applications other than mysqld processes accessing cluster data, but the two designations are actually synonomous; you can, for instance, list parameters for a MySQL server acting as an SQL node in an [api] section.

Замечание

For a discussion of MySQL server options for MySQL Cluster, see Section 16.3.4.2, “MySQL Server Options for MySQL Cluster”; for information about MySQL server system variables relating to MySQL Cluster, see Section 16.3.4.3, “MySQL Cluster System Variables”.

  • Id

    Deprecated5.1.51-ndb-7.1.9
    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 63

    The Id is an integer value used to identify the node in all cluster internal messages. The permitted range of values is 1 to 255 inclusive. This value must be unique for each node in the cluster, regardless of the type of node.

    Замечание

    Data node IDs must be less than 49, regardless of the MySQL Cluster version used. If you plan to deploy a large number of data nodes, it is a good idea to limit the node IDs for API nodes (and management nodes) to values greater than 48.

    NodeId is the preferred parameter name to use when identifying API nodes. (Id continues to be supported for backward compatibility, but is now deprecated and generates a warning when used. It is also subject to future removal.)

  • NodeId

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range1 .. 63

    The NodeId is an integer value used to identify the node in all cluster internal messages. The permitted range of values is 1 to 255 inclusive. This value must be unique for each node in the cluster, regardless of the type of node.

    Замечание

    Data node IDs must be less than 49, regardless of the MySQL Cluster version used. If you plan to deploy a large number of data nodes, it is a good idea to limit the node IDs for API nodes (and management nodes) to values greater than 48.

    NodeId is the preferred parameter name to use when identifying management nodes in MySQL Cluster NDB 7.2 and later. Previously, Id was used for this purpose and this continues to be supported for backward compatibility. Id is now deprecated and generates a warning when used; it is subject to removal in a future release of MySQL Cluster.

  • ExecuteOnComputer

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    This refers to the Id set for one of the computers (hosts) defined in a [computer] section of the configuration file.

  • HostName

    Restart Typesystem
     Permitted Values
    Typestring
    Default
    Range ..

    Specifying this parameter defines the hostname of the computer on which the SQL node (API node) is to reside. To specify a hostname, either this parameter or ExecuteOnComputer is required.

    If no HostName or ExecuteOnComputer is specified in a given [mysql] or [api] section of the config.ini file, then an SQL or API node may connect using the corresponding “slot” from any host which can establish a network connection to the management server host machine. This differs from the default behavior for data nodes, where localhost is assumed for HostName unless otherwise specified.

  • ArbitrationRank

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 2

    This parameter defines which nodes can act as arbitrators. Both MGM nodes and SQL nodes can be arbitrators. A value of 0 means that the given node is never used as an arbitrator, a value of 1 gives the node high priority as an arbitrator, and a value of 2 gives it low priority. A normal configuration uses the management server as arbitrator, setting its ArbitrationRank to 1 (the default for management nodes) and those for all SQL nodes to 0 (the default for SQL nodes).

    By setting ArbitrationRank to 0 on all management and SQL nodes, you can disable arbitration completely. You can also control arbitration by overriding this parameter; to do so, set the Arbitration parameter in the [ndbd default] section of the config.ini global configuration file.

  • ArbitrationDelay

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    Setting this parameter to any other value than 0 (the default) means that responses by the arbitrator to arbitration requests will be delayed by the stated number of milliseconds. It is usually not necessary to change this value.

  • BatchByteSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default32K
    Range1024 .. 1M

    For queries that are translated into full table scans or range scans on indexes, it is important for best performance to fetch records in properly sized batches. It is possible to set the proper size both in terms of number of records (BatchSize) and in terms of bytes (BatchByteSize). The actual batch size is limited by both parameters.

    The speed at which queries are performed can vary by more than 40% depending upon how this parameter is set. In future releases, MySQL Server will make educated guesses on how to set parameters relating to batch size, based on the query type.

    This parameter is measured in bytes and by default is equal to 16KB in MySQL Cluster NDB 7.2.1 and later. (Previously, the default was 32K.)

  • BatchSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64
    Range1 .. 992

    This parameter is measured in number of records and is by default set to 256 (MySQL Cluster NDB 7.2.1 and later; previously, the default was 64). The maximum size is 992.

  • HeartbeatThreadPriority

    Use this parameter to set the scheduling policy and priority of heartbeat threads for management and API nodes. The syntax for setting this parameter is shown here:

    HeartbeatThreadPriority = policy[, priority]
    
    policy:
      {FIFO | RR}
    

    When setting this parameter, you must specify a policy. This is one of FIFO (first in, first in) or RR (round robin). This followed optionally by the priority (an integer).

  • MaxScanBatchSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default256K
    Range32K .. 16M

    The batch size is the size of each batch sent from each data node. Most scans are performed in parallel to protect the MySQL Server from receiving too much data from many nodes in parallel; this parameter sets a limit to the total batch size over all nodes.

    The default value of this parameter is set to 256KB. Its maximum size is 16MB.

  • TotalSendBufferMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default256K
    Range0 .. 4G

    This parameter is available beginning with MySQL Cluster NDB 6.4.0. It is used to determine the total amount of memory to allocate on this node for shared send buffer memory among all configured transporters.

    If this parameter is set, its minimum permitted value is 256KB; the maxmimum is 4294967039. For more detailed information about the behavior and use of TotalSendBufferMemory and configuring send buffer memory parameters in MySQL Cluster, see Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”.

  • AutoReconnect

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Rangefalse .. true

    This parameter is false by default. This forces disconnected API nodes (including MySQL Servers acting as SQL nodes) to use a new connection to the cluster rather than attempting to re-use an existing one, as re-use of connections can cause problems when using dynamically-allocated node IDs. (Bug #45921)

    Замечание

    This parameter can be overridden using the NDB API. For more information, see Ndb_cluster_connection::set_auto_reconnect(), and Ndb_cluster_connection::get_auto_reconnect().

  • DefaultOperationRedoProblemAction

    Restart Type 
     Permitted Values
    Typeenumeration
    Default
    Valid Values

    ABORT

    QUEUE

    This parameter (along with RedoOverCommitLimit and RedoOverCommitCounter) controls the data node's handling of operations when too much time is taken flushing redo logs to disk. This occurs when a given redo log flush takes longer than RedoOverCommitLimit seconds, more than RedoOverCommitCounter times, causing any pending transactions to be aborted.

    When this happens, the node can respond in either of two ways, according to the value of DefaultOperationRedoProblemAction, listed here:

    • ABORT: Any pending operations from aborted transactions are also aborted.

    • QUEUE: Pending operations from transactions that were aborted are queued up to be re-tried.

You can obtain some information from a MySQL server running as a Cluster SQL node using SHOW STATUS in the mysql client, as shown here:

mysql> SHOW STATUS LIKE 'ndb%';
+-----------------------------+---------------+
| Variable_name               | Value         |
+-----------------------------+---------------+
| Ndb_cluster_node_id         | 5             |
| Ndb_config_from_host        | 192.168.0.112 |
| Ndb_config_from_port        | 1186          |
| Ndb_number_of_storage_nodes | 4             |
+-----------------------------+---------------+
4 rows in set (0.02 sec)

For information about these Cluster system status variables, see Section 5.1.5, “Server Status Variables”.

Замечание

To add new SQL or API nodes to the configuration of a running MySQL Cluster, it is necessary to perform a rolling restart of all cluster nodes after adding new [mysqld] or [api] sections to the config.ini file (or files, if you are using more than one management server). This must be done before the new SQL or API nodes can connect to the cluster.

It is not necessary to perform any restart of the cluster if new SQL or API nodes can employ previously unused API slots in the cluster configuration to connect to the cluster.

16.3.2.8. MySQL Cluster TCP/IP Connections

TCP/IP is the default transport mechanism for all connections between nodes in a MySQL Cluster. Normally it is not necessary to define TCP/IP connections; MySQL Cluster automatically sets up such connections for all data nodes, management nodes, and SQL or API nodes.

Замечание

For an exception to this rule, see Section 16.3.2.9, “MySQL Cluster TCP/IP Connections Using Direct Connections”.

To override the default connection parameters, it is necessary to define a connection using one or more [tcp] sections in the config.ini file. Each [tcp] section explicitly defines a TCP/IP connection between two MySQL Cluster nodes, and must contain at a minimum the parameters NodeId1 and NodeId2, as well as any connection parameters to override.

It is also possible to change the default values for these parameters by setting them in the [tcp default] section.

Important

Any [tcp] sections in the config.ini file should be listed last, following all other sections in the file. However, this is not required for a [tcp default] section. This requirement is a known issue with the way in which the config.ini file is read by the MySQL Cluster management server.

Connection parameters which can be set in [tcp] and [tcp default] sections of the config.ini file are listed here:

  • NodeId1

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    NodeId2

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    To identify a connection between two nodes it is necessary to provide their node IDs in the [tcp] section of the configuration file. These are the same unique NodeId (or Id) values for each of these nodes as described in Section 16.3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”.

  • HostName1

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    HostName2

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    The HostName1 and HostName2 parameters can be used to specify specific network interfaces to be used for a given TCP connection between two nodes. The values used for these parameters can be hostnames or IP addresses.

  • OverloadLimit

    This parameter can be used to determine the amount of unsent data that must be present in the send buffer before the connection is considered overloaded. See Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”, for more information.

    In some older releases, the effective value of this parameter was limited by the size of SendBufferMemory; in MySQL Cluster NDB 7.2, the actual value for OverloadLimit (up to the stated maximum of 4G) is used instead.

  • SendBufferMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default256K
    Range64K .. 4G

    TCP transporters use a buffer to store all messages before performing the send call to the operating system. When this buffer reaches 64KB its contents are sent; these are also sent when a round of messages have been executed. To handle temporary overload situations it is also possible to define a bigger send buffer.

    If this parameter is set explicitly, then the memory is not dedicated to each transporter; instead, the value used denotes the hard limit for how much memory (out of the total available memory—that is, TotalSendBufferMemory) that may be used by a single transporter. For more information about configuring dynamic transporter send buffer memory allocation in MySQL Cluster, see Section 16.3.2.12, “Configuring MySQL Cluster Send Buffer Parameters”.

    The default size of the send buffer in MySQL Cluster NDB 7.2 is 2MB, which is the size recommended in most situations. The minimum size is 64 KB; the theoretical maximum is 4 GB.

  • SendSignalId

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse (debug builds: true)
    Range ..

    To be able to retrace a distributed message datagram, it is necessary to identify each message. When this parameter is set to Y, message IDs are transported over the network. This feature is disabled by default in production builds, and enabled in -debug builds.

  • Checksum

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    This parameter is a boolean parameter (enabled by setting it to Y or 1, disabled by setting it to N or 0). It is disabled by default. When it is enabled, checksums for all messages are calculated before they placed in the send buffer. This feature ensures that messages are not corrupted while waiting in the send buffer, or by the transport mechanism.

  • PortNumber (OBSOLETE)

    This formerly specified the port number to be used for listening for connections from other nodes. This parameter should no longer be used; use the ServerPort data node configuration parameter for this purpose instead.

  • ReceiveBufferMemory

    Restart Typenode
     Permitted Values
    Typenumeric
    Default64K
    Range16K .. 4G

    Specifies the size of the buffer used when receiving data from the TCP/IP socket.

    The default value of this parameter is 2MB. The minimum possible value is 16KB; the theoretical maximum is 4GB.

16.3.2.9. MySQL Cluster TCP/IP Connections Using Direct Connections

Setting up a cluster using direct connections between data nodes requires specifying explicitly the crossover IP addresses of the data nodes so connected in the [tcp] section of the cluster config.ini file.

In the following example, we envision a cluster with at least four hosts, one each for a management server, an SQL node, and two data nodes. The cluster as a whole resides on the 172.23.72.* subnet of a LAN. In addition to the usual network connections, the two data nodes are connected directly using a standard crossover cable, and communicate with one another directly using IP addresses in the 1.1.0.* address range as shown:

# Management Server
[ndb_mgmd]
Id=1
HostName=172.23.72.20

# SQL Node
[mysqld]
Id=2
HostName=172.23.72.21

# Data Nodes
[ndbd]
Id=3
HostName=172.23.72.22

[ndbd]
Id=4
HostName=172.23.72.23

# TCP/IP Connections
[tcp]
NodeId1=3
NodeId2=4
HostName1=1.1.0.1
HostName2=1.1.0.2

The HostName1 and HostName2 parameters are used only when specifying direct connections.

The use of direct TCP connections between data nodes can improve the cluster's overall efficiency by enabling the data nodes to bypass an Ethernet device such as a switch, hub, or router, thus cutting down on the cluster's latency. It is important to note that to take the best advantage of direct connections in this fashion with more than two data nodes, you must have a direct connection between each data node and every other data node in the same node group.

16.3.2.10. MySQL Cluster Shared-Memory Connections

MySQL Cluster attempts to use the shared memory transporter and configure it automatically where possible. [shm] sections in the config.ini file explicitly define shared-memory connections between nodes in the cluster. When explicitly defining shared memory as the connection method, it is necessary to define at least NodeId1, NodeId2, and ShmKey. All other parameters have default values that should work well in most cases.

Important

SHM functionality is considered experimental only. It is not officially supported in any current MySQL Cluster release, and testing results indicate that SHM performance is not appreciably greater than when using TCP/IP for the transporter.

For these reasons, you must determine for yourself or by using our free resources (forums, mailing lists) whether SHM can be made to work correctly in your specific case.

  • NodeId1

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    NodeId2

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    To identify a connection between two nodes it is necessary to provide node identifiers for each of them, as NodeId1 and NodeId2.

  • HostName1

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    HostName2

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    The HostName1 and HostName2 parameters can be used to specify specific network interfaces to be used for a given SHM connection between two nodes. The values used for these parameters can be hostnames or IP addresses.

  • ShmKey

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range0 .. 4G

    When setting up shared memory segments, a node ID, expressed as an integer, is used to identify uniquely the shared memory segment to use for the communication. There is no default value.

  • ShmSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default1M
    Range64K .. 4G

    Each SHM connection has a shared memory segment where messages between nodes are placed by the sender and read by the reader. The size of this segment is defined by ShmSize. The default value is 1MB.

  • SendSignalId

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    To retrace the path of a distributed message, it is necessary to provide each message with a unique identifier. Setting this parameter to Y causes these message IDs to be transported over the network as well. This feature is disabled by default in production builds, and enabled in -debug builds.

  • Checksum

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaulttrue
    Range ..

    This parameter is a boolean (Y/N) parameter which is disabled by default. When it is enabled, checksums for all messages are calculated before being placed in the send buffer.

    This feature prevents messages from being corrupted while waiting in the send buffer. It also serves as a check against data being corrupted during transport.

  • SigNum

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range0 .. 4G

    When using the shared memory transporter, a process sends an operating system signal to the other process when there is new data available in the shared memory. Should that signal conflict with with an existing signal, this parameter can be used to change it. This is a possibility when using SHM due to the fact that different operating systems use different signal numbers.

    The default value of SigNum is 0; therefore, it must be set to avoid errors in the cluster log when using the shared memory transporter. Typically, this parameter is set to 10 in the [shm default] section of the config.ini file.

16.3.2.11. SCI Transport Connections in MySQL Cluster

[sci] sections in the config.ini file explicitly define SCI (Scalable Coherent Interface) connections between cluster nodes. Using SCI transporters in MySQL Cluster is supported only when the MySQL binaries are built using --with-ndb-sci=/your/path/to/SCI. The path should point to a directory that contains at a minimum lib and include directories containing SISCI libraries and header files. (See Section 16.3.5, “Using High-Speed Interconnects with MySQL Cluster” for more information about SCI.)

In addition, SCI requires specialized hardware.

It is strongly recommended to use SCI Transporters only for communication between ndbd processes. Note also that using SCI Transporters means that the ndbd processes never sleep. For this reason, SCI Transporters should be used only on machines having at least two CPUs dedicated for use by ndbd processes. There should be at least one CPU per ndbd process, with at least one CPU left in reserve to handle operating system activities.

  • NodeId1

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    NodeId2

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range ..

    To identify a connection between two nodes it is necessary to provide node identifiers for each of them, as NodeId1 and NodeId2.

  • Host1SciId0

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range0 .. 4G

    This identifies the SCI node ID on the first Cluster node (identified by NodeId1).

  • Host1SciId1

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    It is possible to set up SCI Transporters for failover between two SCI cards which then should use separate networks between the nodes. This identifies the node ID and the second SCI card to be used on the first node.

  • Host2SciId0

    Restart Typenode
     Permitted Values
    Typenumeric
    Default
    Range0 .. 4G

    This identifies the SCI node ID on the second Cluster node (identified by NodeId2).

  • Host2SciId1

    Restart Typenode
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 4G

    When using two SCI cards to provide failover, this parameter identifies the second SCI card to be used on the second node.

  • HostName1

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    HostName2

    Restart Typenode
     Permitted Values
    Typestring
    Default
    Range ..

    The HostName1 and HostName2 parameters can be used to specify specific network interfaces to be used for a given SCI connection between two nodes. The values used for these parameters can be hostnames or IP addresses.

  • SharedBufferSize

    Restart Typenode
     Permitted Values
    Typenumeric
    Default10M
    Range64K .. 4G

    Each SCI transporter has a shared memory segment used for communication between the two nodes. Setting the size of this segment to the default value of 1MB should be sufficient for most applications. Using a smaller value can lead to problems when performing many parallel inserts; if the shared buffer is too small, this can also result in a crash of the ndbd process.

  • SendLimit

    Restart Typenode
     Permitted Values
    Typenumeric
    Default8K
    Range128 .. 32K

    A small buffer in front of the SCI media stores messages before transmitting them over the SCI network. By default, this is set to 8KB. Our benchmarks show that performance is best at 64KB but 16KB reaches within a few percent of this, and there was little if any advantage to increasing it beyond 8KB.

  • SendSignalId

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaulttrue
    Range ..

    To trace a distributed message it is necessary to identify each message uniquely. When this parameter is set to Y, message IDs are transported over the network. This feature is disabled by default in production builds, and enabled in -debug builds.

  • Checksum

    Restart Typenode
     Permitted Values
    Typeboolean
    Defaultfalse
    Range ..

    This parameter is a boolean value, and is disabled by default. When Checksum is enabled, checksums are calculated for all messages before they are placed in the send buffer. This feature prevents messages from being corrupted while waiting in the send buffer. It also serves as a check against data being corrupted during transport.

16.3.2.12. Configuring MySQL Cluster Send Buffer Parameters

Formerly, the NDB kernel employed a send buffer whose size was fixed at 2MB for each node in the cluster, this buffer being allocated when the node started. Because the size of this buffer could not be changed after the cluster was started, it was necessary to make it large enough in advance to accommodate the maximum possible load on any transporter socket. However, this was an inefficient use of memory, since much of it often went unused, and could result in large amounts of resources being wasted when scaling up to many API nodes.

This problem was eventually solved (in MySQL Cluster NDB 7.0) by employing a unified send buffer whose memory is allocated dynamically from a pool shared by all transporters. This means that the size of the send buffer can be adjusted as necessary. Configuration of the unified send buffer can accomplished by setting the following parameters:

  • TotalSendBufferMemory This parameter can be set for all types of MySQL Cluster nodes—that is, it can be set in the [ndbd], [mgm], and [api] (or [mysql]) sections of the config.ini file. It represents the total amount of memory (in bytes) to be allocated by each node for which it is set for use among all configured transporters. If set, its minimum is 256KB; the maximum is 4294967039.

    To be backward-compatible with existing configurations, this parameter takes as its default value the sum of the maximum send buffer sizes of all configured transporters, plus an additional 32KB (one page) per transporter. The maximum depends on the type of transporter, as shown in the following table:

    TransporterMaxmimum Send Buffer Size (bytes)
    TCPSendBufferMemory (default = 2M)
    SCISendLimit (default = 8K) plus 16K
    SHM20K

    This enables existing configurations to function in close to the same way as they did with MySQL Cluster NDB 6.3 and earlier, with the same amount of memory and send buffer space available to each transporter. However, memory that is unused by one transporter is not available to other transporters.

  • OverloadLimit This parameter is used in the config.ini file [tcp] section, and denotes the amount of unsent data (in bytes) that must be present in the send buffer before the connection is considered overloaded. When such an overload condition occurs, transactions that affect the overloaded connection fail with NDB API Error 1218 (Send Buffers overloaded in NDB kernel) until the overload status passes. The default value is 0, in which case the effective overload limit is calculated as SendBufferMemory * 0.8 for a given connection. The maximum value for this parameter is 4G.

  • SendBufferMemory This value denotes a hard limit for the amount of memory that may be used by a single transporter out of the entire pool specified by TotalSendBufferMemory. However, the sum of SendBufferMemory for all configured transporters may be greater than the TotalSendBufferMemory that is set for a given node. This is a way to save memory when many nodes are in use, as long as the maximum amount of memory is never required by all transporters at the same time.

16.3.3. Overview of MySQL Cluster Configuration Parameters

The next four sections provide summary tables of MySQL Cluster configuration parameters used in the config.ini file to govern the cluster's functioning. Each table lists the parameters for one of the Cluster node process types (ndbd, ndb_mgmd, and mysqld), and includes the parameter's type as well as its default, mimimum, and maximum values as applicable.

These tables also indicate what type of restart is required (node restart or system restart)—and whether the restart must be done with --initial—to change the value of a given configuration parameter.

When performing a node restart or an initial node restart, all of the cluster's data nodes must be restarted in turn (also referred to as a rolling restart). It is possible to update cluster configuration parameters marked as node online—that is, without shutting down the cluster—in this fashion. An initial node restart requires restarting each ndbd process with the --initial option.

A system restart requires a complete shutdown and restart of the entire cluster. An initial system restart requires taking a backup of the cluster, wiping the cluster file system after shutdown, and then restoring from the backup following the restart.

In any cluster restart, all of the cluster's management servers must be restarted for them to read the updated configuration parameter values.

Important

Values for numeric cluster parameters can generally be increased without any problems, although it is advisable to do so progressively, making such adjustments in relatively small increments. Many of these can be increased online, using a rolling restart.

However, decreasing the values of such parameters—whether this is done using a node restart, node initial restart, or even a complete system restart of the cluster—is not to be undertaken lightly; it is recommended that you do so only after careful planning and testing. This is especially true with regard to those parameters that relate to memory usage and disk space, such as MaxNoOfTables, MaxNoOfOrderedIndexes, and MaxNoOfUniqueHashIndexes. In addition, it is the generally the case that configuration parameters relating to memory and disk usage can be raised using a simple node restart, but they require an initial node restart to be lowered.

Because some of these parameters can be used for configuring more than one type of cluster node, they may appear in more than one of the tables.

Замечание

4294967039 often appears as a maximum value in these tables. This value is defined in the NDBCLUSTER sources as MAX_INT_RNIL and is equal to 0xFFFFFEFF, or 232 – 28 – 1.

16.3.3.1. MySQL Cluster Data Node Configuration Parameters

The summary table in this section provides information about parameters used in the [ndbd] or [ndbd default] sections of a config.ini file for configuring MySQL Cluster data nodes. For detailed descriptions and other additional information about each of these parameters, see Section 16.3.2.6, “Defining MySQL Cluster Data Nodes”.

These parameters also apply to ndbmtd, the multi-threaded version of ndbd. For more information, see Section 16.4.3, “ndbmtd — The MySQL Cluster Data Node Daemon (Multi-Threaded)”.

Restart types.  Changes in MySQL Cluster configuration parameters do not take effect until the cluster is restarted. The type of restart required to change a given parameter is indicated in the summary table as follows:

For more information about restart types, see Section 16.3.3, “Overview of MySQL Cluster Configuration Parameters”.

MySQL Cluster NDB 7.2 supports the addition of new data node groups online, to a running cluster. For more information, see Section 16.5.12, “Adding MySQL Cluster Data Nodes Online”.

Table 16.1. Data Node Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
Arbitration{Disabled|Default|WaitExternal}Default  N
ArbitrationTimeoutmilliseconds3000104GN
BackupDataBufferSizebytes2M 4GN
BackupDataDirpathFileSystemPath  IN
BackupLogBufferSizebytes2M 4GN
BackupMaxWriteSizebytes1M2K4GN
BackupMemorybytes4M 4GN
BackupReportFrequencyseconds  4GN
BackupWriteSizebytes32K2K4GN
BatchSizePerLocalScaninteger2561992N
BuildIndexThreads   128 
CompressedBackup false  N
CompressedLCP false  N
ConnectCheckIntervalDelay 1500 4GN
CrashOnCorruptedTuple OFF   
DataDirpath.  IN
DataMemorybytes80M1M1024GN
DictTracebytesundefined 100N
DiskCheckpointSpeedbytes10M1M4GN
DiskCheckpointSpeedInRestartbytes100M1M4GN
DiskIOThreadPoolthreads8 4GN
Disklesstrue|false (1|0)  1IS
DiskPageBufferMemorybytes64M4M1TN
DiskSyncSizebytes4M32K4GN
ExecuteOnComputername   S
ExtraSendBufferMemorybytes  32GN
FileSystemPathpathDataDir  IN
FileSystemPathDataFiles FileSystemPathDD  IN
FileSystemPathDD FileSystemPath  IN
FileSystemPathUndoFiles FileSystemPathDD  IN
FragmentLogFileSizebytes16M4M1GIN
HeartbeatIntervalDbApimilliseconds15001004GN
HeartbeatIntervalDbDbmilliseconds1500104GN
HeartbeatOrder   65535S
HostNamename or IP addresslocalhost  S
Idunsigned 148N
IndexMemorybytes18M1M1TN
InitFragmentLogFilessparse|full   IN
InitialLogFileGroup [see documentation]  S
InitialNoOfOpenFilesfiles27204GN
InitialTablespace [see documentation]  S
IOThreadPoolthreads8 4GN
LockExecuteThreadToCPUCPU ID64K 64KN
LockMaintThreadsToCPUCPU ID64K 64KN
LockPagesInMainMemory   2N
LogLevelCheckpointlog level  15IN
LogLevelCongestionlevelr  15N
LogLevelConnectioninteger  15N
LogLevelErrorinteger  15N
LogLevelInfointeger  15N
LogLevelNodeRestartinteger  15N
LogLevelShutdowninteger  15N
LogLevelStartupinteger1 15N
LogLevelStatisticinteger  15N
LongMessageBufferbytes1M512K4GN
MaxAllocateunsigned32M1M1GN
MaxBufferedEpochsepochs100 100000N
MaxDMLOperationsPerTransactionoperations (DML)4294967295324294967295N
MaxLCPStartDelayseconds  600N
MaxNoOfAttributesinteger1000324GN
MaxNoOfConcurrentIndexOperationsinteger8K 4GN
MaxNoOfConcurrentOperationsinteger32K324GN
MaxNoOfConcurrentScansinteger2562500N
MaxNoOfConcurrentSubOperationsunsigned256 4GN
MaxNoOfConcurrentTransactionsinteger4096324GS
MaxNoOfFiredTriggersinteger4000 4GN
MaxNoOfLocalOperationsintegerUNDEFINED324GN
MaxNoOfLocalScansintegerUNDEFINED324GN
MaxNoOfOpenFilesunsigned 204GN
MaxNoOfOrderedIndexesinteger128 4GN
MaxNoOfSavedMessagesinteger25 4GN
MaxNoOfSubscribersunsigned  4GN
MaxNoOfSubscriptionsunsigned  4GN
MaxNoOfTablesinteger128820320N
MaxNoOfTriggersinteger768 4GN
MaxNoOfUniqueHashIndexesinteger64 4GN
MaxParallelScansPerFragmentbytes3211GN
MaxStartFailRetriesunsigned3 4GN
MemReportFrequencyunsigned  4GN
MinFreePctunsigned5 100N
NodeGroup   65536IS
NodeIdunsigned 148N
NoOfDiskPagesToDiskAfterRestartACC8K pages/100 milliseconds2014GN
NoOfDiskPagesToDiskAfterRestartTUP8K pages/100 milliseconds4014GN
NoOfDiskPagesToDiskDuringRestartACC8K pages/100 milliseconds2014GN
NoOfDiskPagesToDiskDuringRestartTUP8K pages/100 milliseconds4014GN
NoOfFragmentLogFilesinteger1634GIN
NoOfReplicasintegerNone14IS
Numa    N
ODirectboolean  1N
RealtimeScheduler false  N
RedoBufferbytes8M1M4GN
RedoOverCommitCounter 3 4GN
RedoOverCommitLimitseconds20 4GN
ReservedSendBufferMemorybytes256K 4GN
RestartOnErrorInserterror code2 4N
SchedulerExecutionTimerµsec50 11000N
SchedulerSpinTimerµsec  500N
ServerPortunsigned 164KN
SharedGlobalMemorybytes20M 64TN
StartFailRetryDelayunsigned  4GN
StartFailureTimeoutmilliseconds  4GN
StartNoNodeGroupTimeoutmilliseconds15000 4294967039N
StartPartialTimeoutmilliseconds30000 4GN
StartPartitionedTimeoutmilliseconds60000 4GN
StartupStatusReportFrequencyseconds   N
StopOnErrortrue|false (1|0)true  N
StringMemory% or bytes25 4GS
TcpBind_INADDR_ANY false  N
ThreadConfig [none]  N
TimeBetweenEpochsmilliseconds100 32000N
TimeBetweenEpochsTimeoutmilliseconds4000 256000N
TimeBetweenGlobalCheckpointsmilliseconds20001032000N
TimeBetweenInactiveTransactionAbortCheckmilliseconds100010004GN
TimeBetweenLocalCheckpointsnumber of 4-byte words, as a base-2 logarithm20 31N
TimeBetweenWatchDogCheckmilliseconds6000704GN
TimeBetweenWatchDogCheckInitialmilliseconds6000704GN
TotalSendBufferMemorybytes256K 4GN
TransactionBufferMemorybytes1M1K4GN
TransactionDeadlockDetectionTimeoutmilliseconds1200504GN
TransactionInactiveTimeoutmilliseconds4G 4GN
TwoPassInitialNodeRestart FALSE  N
UndoDataBufferunsigned16M1M4GN
UndoIndexBufferunsigned2M1M4GN

16.3.3.2. MySQL Cluster Management Node Configuration Parameters

The summary table in this section provides information about parameters used in the [ndb_mgmd] or [mgm] sections of a config.ini file for configuring MySQL Cluster management nodes. For detailed descriptions and other additional information about each of these parameters, see Section 16.3.2.5, “Defining a MySQL Cluster Management Server”.

Restart types.  Changes in MySQL Cluster configuration parameters do not take effect until the cluster is restarted. The type of restart required to change a given parameter is indicated in the summary table as follows:

For more information about restart types, see Section 16.3.3, “Overview of MySQL Cluster Configuration Parameters”.

Table 16.2. Management Node Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
ArbitrationDelaymilliseconds  4GN
ArbitrationRank0-21 2N
DataDirpath.  N
ExecuteOnComputername   S
HeartbeatThreadPriority none   
HostNamename or IP address   S
Idunsigned 163N
LogDestination{CONSOLE|SYSLOG|FILE}FILE:filename=ndb_nodeid_cluster.log,maxsize=1000000,maxfiles=6  N
MaxNoOfSavedEventsunsigned100 4GN
NodeIdunsigned 163N
PortNumberunsigned1186 64KN
PortNumberStatsunsigned  64KN
wan false  N
Замечание

After making changes in a management node's configuration, it is necessary to perform a rolling restart of the cluster for the new configuration to take effect. See Section 16.3.2.5, “Defining a MySQL Cluster Management Server”, for more information.

To add new management servers to a running MySQL Cluster, it is also necessary perform a rolling restart of all cluster nodes after modifying any existing config.ini files. For more information about issues arising when using multiple management nodes, see Section 16.1.6.10, “Limitations Relating to Multiple MySQL Cluster Nodes”.

16.3.3.3. MySQL Cluster SQL Node and API Node Configuration Parameters

The summary table in this section provides information about parameters used in the [mysqld] and [api] sections of a config.ini file for configuring MySQL Cluster SQL nodes and API nodes. For detailed descriptions and other additional information about each of these parameters, see Section 16.3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”.

Замечание

For a discussion of MySQL server options for MySQL Cluster, see Section 16.3.4.2, “MySQL Server Options for MySQL Cluster”; for information about MySQL server system variables relating to MySQL Cluster, see Section 16.3.4.3, “MySQL Cluster System Variables”.

Restart types.  Changes in MySQL Cluster configuration parameters do not take effect until the cluster is restarted. The type of restart required to change a given parameter is indicated in the summary table as follows:

For more information about restart types, see Section 16.3.3, “Overview of MySQL Cluster Configuration Parameters”.

Table 16.3. SQL Node/API Node Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
ArbitrationDelaymilliseconds  4GN
ArbitrationRank0-2  2N
AutoReconnect falsefalsetrueN
BatchByteSizebytes32K10241MN
BatchSizerecords641992N
ConnectionMap    N
DefaultOperationRedoProblemAction     
ExecuteOnComputername   S
HeartbeatThreadPriority none   
HostNamename or IP address   S
Idunsigned 163N
MaxScanBatchSizebytes256K32K16MN
NodeIdunsigned 163N
TotalSendBufferMemorybytes256K 4GN
wan false  N
Замечание

To add new SQL or API nodes to the configuration of a running MySQL Cluster, it is necessary to perform a rolling restart of all cluster nodes after adding new [mysqld] or [api] sections to the config.ini file (or files, if you are using more than one management server). This must be done before the new SQL or API nodes can connect to the cluster.

It is not necessary to perform any restart of the cluster if new SQL or API nodes can employ previously unused API slots in the cluster configuration to connect to the cluster.

16.3.3.4. Other MySQL Cluster Configuration Parameters

The summary tables in this section provide information about parameters used in the [computer], [tcp], [shm], and [sci] sections of a config.ini file for configuring MySQL Cluster management nodes. For detailed descriptions and other additional information about individual parameters, see Section 16.3.2.8, “MySQL Cluster TCP/IP Connections”, Section 16.3.2.10, “MySQL Cluster Shared-Memory Connections”, or Section 16.3.2.11, “SCI Transport Connections in MySQL Cluster”, as appropriate.

Restart types.  Changes in MySQL Cluster configuration parameters do not take effect until the cluster is restarted. The type of restart required to change a given parameter is indicated in the summary tables as follows:

For more information about restart types, see Section 16.3.3, “Overview of MySQL Cluster Configuration Parameters”.

Table 16.4. COMPUTER Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
HostNamename or IP address   S
Idstring   IN

Table 16.5. TCP Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
Checksum false  N
Groupunsigned55 200N
NodeId1    N
NodeId2    N
NodeIdServer    N
OverloadLimitbytes  4GN
PortNumberunsigned  64KN
Proxy    N
ReceiveBufferMemorybytes64K16K4GN
SendBufferMemoryunsigned256K64K4GN
SendSignalId false (debug builds: true)  N
TCP_MAXSEG_SIZEunsigned  2GN
TCP_RCV_BUF_SIZEunsigned7008012GN
TCP_SND_BUF_SIZEunsigned7154012GN
TcpBind_INADDR_ANY false  N

Table 16.6. SHM Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
Checksum true  N
Groupunsigned35 200N
NodeId1    N
NodeId2    N
NodeIdServer    N
OverloadLimitbytes  4GN
PortNumberunsigned  64KN
SendSignalId false  N
ShmKeyunsigned  4GN
ShmSizebytes1M64K4GN
Signumunsigned  4GN

Table 16.7. SCI Configuration Parameters

NameType/UnitsDefaultMin ValueMax ValueRestart Type
Checksum false  N
Groupunsigned15 200N
Host1SciId0unsigned  4GN
Host1SciId1unsigned  4GN
Host2SciId0unsigned  4GN
Host2SciId1unsigned  4GN
NodeId1    N
NodeId2    N
NodeIdServer    N
OverloadLimitbytes  4GN
PortNumberunsigned  64KN
SendLimitunsigned8K12832KN
SendSignalId true  N
SharedBufferSizeunsigned10M64K4GN

16.3.4. MySQL Server Options and Variables for MySQL Cluster

This section provides information about MySQL server options, server and status variables that are specific to MySQL Cluster. For general information on using these, and for other options and variables not specific to MySQL Cluster, see Section 5.1, “The MySQL Server”.

For MySQL Cluster configuration parameters used in the cluster confiuration file (usually named config.ini), see Section 16.3, “MySQL Cluster Configuration”.

16.3.4.1. MySQL Cluster mysqld Option and Variable Reference

The following table provides a list of the command-line options, server and status variables applicable within mysqld when it is running as an SQL node in a MySQL Cluster. For a table showing all command-line options, server and status variables available for use with mysqld, see Section 5.1.1, “Server Option and Variable Reference”.

Table 16.8. MySQL Server Option and Variable Reference for MySQL Cluster

NameCmd-LineOption fileSystem VarStatus VarVar ScopeDynamic
Handler_discover   YesBothNo
have_ndbcluster  Yes GlobalNo
Ndb_api_bytes_received_count   YesGlobalNo
Ndb_api_bytes_received_count_session   YesSessionNo
Ndb_api_bytes_received_count_slave   YesGlobalNo
Ndb_api_bytes_sent_count   YesGlobalNo
Ndb_api_bytes_sent_count_session   YesSessionNo
Ndb_api_bytes_sent_count_slave   YesGlobalNo
Ndb_api_event_bytes_count   YesGlobalNo
Ndb_api_event_bytes_count_injector   YesGlobalNo
Ndb_api_event_data_count   YesGlobalNo
Ndb_api_event_data_count_injector   YesGlobalNo
Ndb_api_event_nondata_count   YesGlobalNo
Ndb_api_event_nondata_count_injector   YesGlobalNo
Ndb_api_pk_op_count   YesGlobalNo
Ndb_api_pk_op_count_session   YesSessionNo
Ndb_api_pk_op_count_slave   YesGlobalNo
Ndb_api_pruned_scan_count   YesGlobalNo
Ndb_api_pruned_scan_count_session   YesSessionNo
Ndb_api_pruned_scan_count_slave   YesGlobalNo
Ndb_api_range_scan_count   YesGlobalNo
Ndb_api_range_scan_count_session   YesSessionNo
Ndb_api_range_scan_count_slave   YesGlobalNo
Ndb_api_read_row_count   YesGlobalNo
Ndb_api_read_row_count_session   YesSessionNo
Ndb_api_read_row_count_slave   YesGlobalNo
Ndb_api_scan_batch_count   YesGlobalNo
Ndb_api_scan_batch_count_session   YesSessionNo
Ndb_api_scan_batch_count_slave   YesGlobalNo
Ndb_api_table_scan_count   YesGlobalNo
Ndb_api_table_scan_count_session   YesSessionNo
Ndb_api_table_scan_count_slave   YesGlobalNo
Ndb_api_trans_abort_count   YesGlobalNo
Ndb_api_trans_abort_count_session   YesSessionNo
Ndb_api_trans_abort_count_slave   YesGlobalNo
Ndb_api_trans_close_count   YesGlobalNo
Ndb_api_trans_close_count_session   YesSessionNo
Ndb_api_trans_close_count_slave   YesGlobalNo
Ndb_api_trans_commit_count   YesGlobalNo
Ndb_api_trans_commit_count_session   YesSessionNo
Ndb_api_trans_commit_count_slave   YesGlobalNo
Ndb_api_trans_local_read_row_count   YesGlobalNo
Ndb_api_trans_local_read_row_count_session   YesSessionNo
Ndb_api_trans_local_read_row_count_slave   YesGlobalNo
Ndb_api_trans_start_count   YesGlobalNo
Ndb_api_trans_start_count_session   YesSessionNo
Ndb_api_trans_start_count_slave   YesGlobalNo
Ndb_api_uk_op_count   YesGlobalNo
Ndb_api_uk_op_count_session   YesSessionNo
Ndb_api_uk_op_count_slave   YesGlobalNo
Ndb_api_wait_exec_complete_count   YesGlobalNo
Ndb_api_wait_exec_complete_count_session   YesSessionNo
Ndb_api_wait_exec_complete_count_slave   YesGlobalNo
Ndb_api_wait_meta_request_count   YesGlobalNo
Ndb_api_wait_meta_request_count_session   YesSessionNo
Ndb_api_wait_meta_request_count_slave   YesGlobalNo
Ndb_api_wait_nanos_count   YesGlobalNo
Ndb_api_wait_nanos_count_session   YesSessionNo
Ndb_api_wait_nanos_count_slave   YesGlobalNo
Ndb_api_wait_scan_result_count   YesGlobalNo
Ndb_api_wait_scan_result_count_session   YesSessionNo
Ndb_api_wait_scan_result_count_slave   YesGlobalNo
ndb_autoincrement_prefetch_szYesYesYes BothYes
ndb-batch-sizeYesYesYes GlobalNo
ndb-blob-read-batch-bytesYesYesYes BothYes
ndb-blob-write-batch-bytesYesYesYes BothYes
ndb_cache_check_timeYesYesYes GlobalYes
ndb-cluster-connection-poolYesYesYesYesGlobalNo
Ndb_cluster_node_id   YesBothNo
Ndb_config_from_host   YesBothNo
Ndb_conflict_fn_epoch   YesGlobalNo
Ndb_conflict_fn_epoch_trans   YesGlobalNo
Ndb_conflict_fn_max   YesGlobalNo
Ndb_conflict_fn_old   YesGlobalNo
Ndb_conflict_trans_conflict_commit_count   YesGlobalNo
Ndb_conflict_trans_detect_iter_count   YesGlobalNo
Ndb_conflict_trans_reject_count   YesGlobalNo
Ndb_conflict_trans_row_conflict_count   YesGlobalNo
Ndb_conflict_trans_row_reject_count   YesGlobalNo
ndb-connectstringYesYes    
ndb-deferred-constraintsYesYes  BothYes
- Variable: ndb_deferred_constraints  Yes BothYes
ndb_deferred_constraintsYesYesYes BothYes
ndb_distributionYesYesYes BothYes
ndb-distributionYesYes  BothYes
- Variable: ndb_distribution  Yes BothYes
ndb_execute_count   YesGlobalNo
ndb_extra_loggingYesYesYes GlobalYes
ndb_force_sendYesYesYes BothYes
ndb_index_stat_cache_entriesYesYes    
ndb_index_stat_enableYesYes    
ndb_index_stat_update_freqYesYes    
ndb_join_pushdown  Yes GlobalNo
ndb-log-apply-statusYesYes  GlobalNo
- Variable: ndb_log_apply_status  Yes GlobalNo
ndb_log_binYes Yes BothYes
ndb_log_binlog_indexYes Yes GlobalYes
ndb_log_empty_epochsYesYesYes GlobalYes
ndb-log-empty-epochsYesYesYes GlobalYes
ndb_log_orig  Yes GlobalNo
ndb-log-transaction-idYesYes  GlobalNo
- Variable: ndb_log_transaction_id  Yes GlobalNo
ndb_log_transaction_id  Yes GlobalNo
ndb-log-update-as-writeYesYesYes GlobalYes
ndb_log_updated_onlyYesYesYes GlobalYes
ndb-mgmd-hostYesYes    
ndb-nodeidYesYes YesGlobalNo
Ndb_number_of_data_nodes   YesGlobalNo
ndb_optimization_delay  Yes GlobalYes
ndb_optimized_node_selectionYesYes    
ndb_pruned_scan_count   YesGlobalNo
Ndb_pushed_queries_defined   YesGlobalNo
Ndb_pushed_queries_dropped   YesGlobalNo
Ndb_pushed_queries_executed   YesGlobalNo
ndb_pushed_reads   YesGlobalNo
ndb_report_thresh_binlog_epoch_slipYesYes    
ndb_report_thresh_binlog_mem_usageYesYes    
ndb_scan_count   YesGlobalNo
ndb_table_no_logging  Yes SessionYes
ndb_table_temporary  Yes SessionYes
ndb_use_copying_alter_table  Yes BothNo
ndb_use_exact_count  Yes BothYes
ndb_use_transactionsYesYesYes BothYes
ndb-wait-connectedYesYesYes GlobalNo
ndb-wait-setupYesYesYes GlobalNo
ndbclusterYesYes    
- Variable: have_ndbcluster      
ndbinfo_database  Yes GlobalNo
ndbinfo_max_bytesYes Yes BothYes
ndbinfo_max_rowsYes Yes BothYes
ndbinfo_show_hiddenYes Yes BothYes
ndbinfo_table_prefixYes Yes BothYes
ndbinfo_version  Yes GlobalNo
server-id-bitsYesYes  GlobalNo
- Variable: server_id_bits  Yes GlobalNo
skip-ndbclusterYesYes    
slave_allow_batchingYesYesYes GlobalYes

16.3.4.2. MySQL Server Options for MySQL Cluster

This section provides descriptions of mysqld server options relating to MySQL Cluster. For information about mysqld options not specific to MySQL Cluster, and for general information about the use of options with mysqld, see Section 5.1.2, “Server Command Options”.

For information about command-line options used with other MySQL Cluster processes (ndbd, ndb_mgmd, and ndb_mgm), see Section 16.4.23, “Options Common to MySQL Cluster Programs”. For information about command-line options used with NDB utility programs (such as ndb_desc, ndb_size.pl, and ndb_show_tables), see Section 16.4, “MySQL Cluster Programs”.

  • --ndb-batch-size=#

    Command-Line Format--ndb-batch-size
    Option-File Formatndb-batch-size
    Variable Namendb_batch_size
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default32768
    Range0 .. 31536000

    This sets the size in bytes that is used for NDB transaction batches.

  • --ndb-cluster-connection-pool=#

    Command-Line Format--ndb-cluster-connection-pool
    Option-File Formatndb-cluster-connection-pool
    Variable Namendb_cluster_connection_pool
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default1
    Range1 .. 63

    By setting this option to a value greater than 1 (the default), a mysqld process can use multiple connections to the cluster, effectively mimicking several SQL nodes. Each connection requires its own [api] or [mysqld] section in the cluster configuration (config.ini) file, and counts against the maximum number of API connections supported by the cluster.

    Suppose that you have 2 cluster host computers, each running an SQL node whose mysqld process was started with --ndb-cluster-connection-pool=4; this means that the cluster must have 8 API slots available for these connections (instead of 2). All of these connections are set up when the SQL node connects to the cluster, and are allocated to threads in a round-robin fashion.

    This option is useful only when running mysqld on host machines having multiple CPUs, multiple cores, or both. For best results, the value should be smaller than the total number of cores available on the host machine. Setting it to a value greater than this is likely to degrade performance severely.

    Important

    Because each SQL node using connection pooling occupies multiple API node slots—each slot having its own node ID in the cluster—you must not use a node ID as part of the cluster connectstring when starting any mysqld process that employs connection pooling.

    Setting a node ID in the connectstring when using the --ndb-cluster-connection-pool option causes node ID allocation errors when the SQL node attempts to connect to the cluster.

    Замечание

    In some older relases of MySQL Cluster prior to MySQL Cluster NDB 7.2, there was also a separate status variable corresponding to this option; however, the status variable was removed as redundant as of these versions. (Bug #60119)

  • --ndb-blob-read-batch-bytes=bytes

    Command-Line Format--ndb-blob-read-batch-bytes
    Option-File Formatndb-blob-read-batch-bytes
    Variable Namendb_blob_read_batch_bytes
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default65535
    Range0 .. 4294967295

    This option can be used to set the size (in bytes) for batching of BLOB data reads in MySQL Cluster applications. When this batch size is exceeded by the amount of BLOB data to be read within the current transaction, any pending BLOB read operations are immediately executed.

    The maximum value for this option is 4294967295; the default is 65535. Setting it to 0 has the effect of disabling BLOB read batching.

    Замечание

    In NDB API applications, you can control BLOB write batching with the setMaxPendingBlobReadBytes() and getMaxPendingBlobReadBytes() methods.

  • --ndb-blob-write-batch-bytes=bytes

    Command-Line Format--ndb-blob-write-batch-bytes
    Option-File Formatndb-blob-write-batch-bytes
    Variable Namendb_blob_write_batch_bytes
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default65535
    Range0 .. 4294967295

    This option can be used to set the size (in bytes) for batching of BLOB data writes in MySQL Cluster applications. When this batch size is exceeded by the amount of BLOB data to be written within the current transaction, any pending BLOB write operations are immediately executed.

    The maximum value for this option is 4294967295; the default is 65535. Setting it to 0 has the effect of disabling BLOB write batching.

    Замечание

    In NDB API applications, you can control BLOB write batching with the setMaxPendingBlobWriteBytes() and getMaxPendingBlobWriteBytes() methods.

  • --ndb-connectstring=connect_string

    Command-Line Format--ndb-connectstring
    Option-File Formatndb-connectstring
     Permitted Values
    Typestring

    When using the NDBCLUSTER storage engine, this option specifies the management server that distributes cluster configuration data. See Section 16.3.2.3, “The MySQL Cluster Connectstring”, for syntax.

  • --ndb-deferred-constraints=[TRUE|FALSE]

    Command-Line Format--ndb-deferred-constraints
    Option-File Formatndb-deferred-constraints
    Option Sets VariableYes, ndb_deferred_constraints
    Variable Namendb-deferred-constraints
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    Defaultfalse
    Rangefalse .. true

    Controls whether or not constraint checks are deferred, where these are supported. OFF is the default.

    This option was added in MySQL Cluster NDB 7.0.28 and MySQL Cluster NDB 7.1.17.

  • --ndb-distribution=[KEYHASH|LINHASH]

    Command-Line Format--ndb-distribution={KEYHASH|LINHASH}
    Option-File Formatndb-distribution
    Option Sets VariableYes, ndb_distribution
    Variable Namendb-distribution
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeenumeration
    DefaultKEYHASH
    Valid Values

    LINHASH

    KEYHASH

    Controls the default distribution method for NDB tables. Can be set to either of KEYHASH (key hashing) or LINHASH (linear hashing). KEYHASH is the default.

  • --ndb-mgmd-host=host[:port]

    Command-Line Format--ndb-mgmd-host=host[:port]
    Option-File Formatndb-mgmd-host
     Permitted Values
    Typestring
    Defaultlocalhost:1186

    Can be used to set the host and port number of a single management server for the program to connect to. If the program requires node IDs or references to multiple management servers (or both) in its connection information, use the --ndb-connectstring option instead.

  • --ndbcluster

    Command-Line Format--ndbcluster
    Option-File Formatndbcluster
    Option Sets VariableYes, have_ndbcluster
    Disabled byskip-ndbcluster
     Permitted Values
    Typeboolean
    DefaultFALSE

    The NDBCLUSTER storage engine is necessary for using MySQL Cluster. If a mysqld binary includes support for the NDBCLUSTER storage engine, the engine is disabled by default. Use the --ndbcluster option to enable it. Use --skip-ndbcluster to explicitly disable the engine.

  • --ndb-log-apply-status

    Command-Line Format--ndb-log-apply-status
    Option-File Formatndb-log-apply-status
    Option Sets VariableYes, ndb_log_apply_status
    Variable Namendb_log_apply_status
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean
    DefaultOFF

    Causes a slave mysqld to log any updates received from its immediate master to the mysql.ndb_apply_status table in its own binary log using its own server ID rather than the server ID of the master. In a circular or chain replication setting, this allows such updates to propagate to the mysql.ndb_apply_status tables of any MySQL servers configured as slaves of the current mysqld.

    In a chain replication setup, using this option allows downstream (slave) clusters to be aware of their positions relative to all of their upstream contributors (masters).

    In a circular replication setup, this option causes changes to ndb_apply_status tables to complete the entire circuit, eventually propagating back to the originating MySQL Cluster. This also allows a cluster acting as a master to see when its changes (epochs) have been applied to the other clusters in the circle.

    This option has no effect unless the MySQL server is started with the --ndbcluster option.

  • --ndb-log-transaction-id

    Version Introduced5.5.15-ndb-7.2.1
    Command-Line Format--ndb-log-transaction-id[={0|1}]
    Option-File Formatndb-log-transaction-id
    Option Sets VariableYes, ndb_log_transaction_id
    Variable Namendb_log_transaction_id
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean
    DefaultOFF

    Causes a slave mysqld to write the NDB transaction ID in each row of the binary log. Such logging requires the use of the Version 2 event format for the binary log; thus, --log-bin-use-v1-row-events must be set to FALSE in order to use this option.

    This option is available beginning with MySQL Cluster NDB 7.2.1 (and is not supported in mainline MySQL Server 5.5). It is required to enable MySQL Cluster Replication conflict detection and resolution using the NDB$EPOCH_TRANS() function introduced in the same MySQL Cluster release.

    The default value is FALSE.

    For more information, see Section 16.6.11, “MySQL Cluster Replication Conflict Resolution”.

  • --ndb-nodeid=#

    Command-Line Format--ndb-nodeid=#
    Option-File Formatndb-nodeid
    Variable NameNdb_cluster_node_id
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Range1 .. 255

    Set this MySQL server's node ID in a MySQL Cluster.

    The --ndb-nodeid option overrides any node ID set with --ndb-connectstring, regardless of the order in which the two options are used.

    In addition, if --ndb-nodeid is used, then either a matching node ID must be found in a [mysqld] or [api] section of config.ini, or there must be an “open[mysqld] or [api] section in the file (that is, a section without a NodeId or Id parameter specified). This is also true if the node ID is specified as part of the connectstring.

    Regardless of how the node ID is determined, its is shown as the value of the global status variable Ndb_cluster_node_id in the output of SHOW STATUS, and as cluster_node_id in the connection row of the output of SHOW ENGINE NDBCLUSTER STATUS.

    For more information about node IDs for MySQL Cluster SQL nodes, see Section 16.3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”.

  • --ndb-log-empty-epochs=[0|1]

    Command-Line Format--ndb-log-empty-epochs
    Option-File Formatndb-log-empty-epochs
    Variable Namendb_log_empty_epochs
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultOFF

    Causes epochs during which there were no changes to be written to the ndb_apply_status and ndb_binlog_index tables, even when --log-slave-updates is enabled.

    By default this option is disabled. Disabling --ndb-log-empty-epochs causes epoch transactions with no changes not to be written to the binary log, although a row is still written even for an empty epoch in ndb_binlog_index.

    Because --ndb-log-empty-epochs=1 causes the size of ndb_binlog_index table to increase independently of the size of the binary log, users should be prepared to manage the growth of this table, even if they expect the cluster to be idle a large part of the time.

  • --server-id-bits=#

    Command-Line Format--server-id-bits=#
    Option-File Formatserver-id-bits
    Option Sets VariableYes, server_id_bits
    Variable Nameserver_id_bits
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default32
    Range7 .. 32

    This option indicates the number of least significant bits within the 32-bit server_id which actually identify the server. Indicating that the server is actually identified by fewer than 32 bits makes it possible for some of the remaining bits to be used for other purposes, such as storing user data generated by applications using the NDB API's Event API within the AnyValue of an OperationOptions structure (MySQL Cluster uses the AnyValue to store the server ID).

    When extracting the effective server ID from server_id for purposes such as detection of replication loops, the server ignores the remaining bits. The --server-id-bits option is used to mask out any irrelevant bits of server_id in the IO and SQL threads when deciding whether an event should be ignored based on the server ID.

    This data can be read from the binary log by mysqlbinlog, provided that it is run with its own --server-id-bits option set to 32 (the default).

    The value of server_id must be less than 2 ^ server_id_bits; otherwise, mysqld refuses to start.

    This system variable is supported only by MySQL Cluster. It is not supported in the standard MySQL 5.5 Server.

  • --skip-ndbcluster

    Command-Line Format--skip-ndbcluster
    Option-File Formatskip-ndbcluster

    Disable the NDBCLUSTER storage engine. This is the default for binaries that were built with NDBCLUSTER storage engine support; the server allocates memory and other resources for this storage engine only if the --ndbcluster option is given explicitly. See Section 16.3.1, “Quick Test Setup of MySQL Cluster”, for an example.

  • --ndb-wait-connected=seconds

    Command-Line Format--ndb-wait-connected=#
    Option-File Formatndb-wait-connected
    Variable Namendb-wait-connected
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default0
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default30
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default30
    Range0 .. 31536000

    This option sets the period of time that the MySQL server waits for connections to MySQL Cluster management and data nodes to be established before accepting MySQL client connections. The time is specified in seconds. The default value is 30.

  • --ndb-wait-setup=seconds

    Command-Line Format--ndb-wait-setup=#
    Option-File Formatndb-wait-setup
    Variable Namendb-wait-setup
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default15
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default15
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default30
    Range0 .. 31536000
     Permitted Values
    Typenumeric
    Default30
    Range0 .. 31536000

    This variable shows the period of time that the MySQL server waits for the NDB storage engine to complete setup before timing out and treating NDB as unavailable. The time is specified in seconds. The default value is 30.

  • --ndb_optimization_delay=milliseconds

    Variable Namendb_optimization_delay
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default10
    Range0 .. 100000

    Set the number of milliseconds to wait between sets of rows by OPTIMIZE TABLE statements on NDB tables. The default is 15.

16.3.4.3. MySQL Cluster System Variables

This section provides detailed information about MySQL server system variables that are specific to MySQL Cluster and the NDB storage engine. For system variables not specific to MySQL Cluster, see Section 5.1.3, “Server System Variables”. For general information on using system variables, see Section 5.1.4, “Using System Variables”.

  • have_ndbcluster

    Variable Namehave_ndbcluster
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean

    YES if mysqld supports NDBCLUSTER tables. DISABLED if --skip-ndbcluster is used.

    This variable is deprecated and is removed in MySQL 5.6. Use SHOW ENGINES instead.

  • multi_range_count

    Command-Line Format--multi_range_count=#
    Option-File Formatmulti_range_count
    Option Sets VariableYes, multi_range_count
    Variable Namemulti_range_count
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default256
    Range1 .. 4294967295

    The maximum number of ranges to send to a table handler at once during range selects. The default value is 256. Sending multiple ranges to a handler at once can improve the performance of certain selects dramatically. This is especially true for the NDBCLUSTER table handler, which needs to send the range requests to all nodes. Sending a batch of those requests at once reduces communication costs significantly.

    This variable is deprecated in MySQL 5.1, and is no longer supported in MySQL 5.5, in which arbitrarily long lists of ranges can be processed.

  • ndb_autoincrement_prefetch_sz

    Command-Line Format--ndb_autoincrement_prefetch_sz
    Option-File Formatndb_autoincrement_prefetch_sz
    Option Sets VariableYes, ndb_autoincrement_prefetch_sz
    Variable Namendb_autoincrement_prefetch_sz
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default1
    Range1 .. 256

    Determines the probability of gaps in an autoincremented column. Set it to 1 to minimize this. Setting it to a high value for optimization—makes inserts faster, but decreases the likelihood that consecutive autoincrement numbers will be used in a batch of inserts. Default value: 32. Minimum value: 1.

    This variable affects only the number of AUTO_INCREMENT IDs that are fetched between statements; within a given statement, at least 32 IDs are obtained at a time. The default value for ndb_autoincrement_prefetch_sz is 1, to increase the speed of statements inserting single rows.

    The maximum value for ndb_autoincrement_prefetch_sz is 65536.

  • ndb_cache_check_time

    Command-Line Format--ndb_cache_check_time
    Option-File Formatndb_cache_check_time
    Option Sets VariableYes, ndb_cache_check_time
    Variable Namendb_cache_check_time
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default0

    The number of milliseconds that elapse between checks of MySQL Cluster SQL nodes by the MySQL query cache. Setting this to 0 (the default and minimum value) means that the query cache checks for validation on every query.

    The recommended maximum value for this variable is 1000, which means that the check is performed once per second. A larger value means that the check is performed and possibly invalidated due to updates on different SQL nodes less often. It is generally not desirable to set this to a value greater than 2000.

  • ndb_deferred_constraints

    Command-Line Format--ndb-deferred-constraints
    Option-File Formatndb_deferred_constraints
    Option Sets VariableYes, ndb_deferred_constraints
    Variable Namendb_deferred_constraints
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    Defaultfalse
    Rangefalse .. true

    Controls whether or not constraint checks are deferred, where these are supported. OFF is the default.

  • ndb_distribution

    Command-Line Format--ndb-distribution={KEYHASH|LINHASH}
    Option-File Formatndb_distribution
    Variable Namendb_distribution={KEYHASH|LINHASH}
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeenumeration
    DefaultKEYHASH
    Valid Values

    LINHASH

    KEYHASH

    Controls the default distribution method for NDB tables. Can be set to either of KEYHASH (key hashing) or LINHASH (linear hashing). KEYHASH is the default.

  • ndb_extra_logging

    Command-Line Formatndb_extra_logging=#
    Option-File Formatndb_extra_logging
    Variable Namendb_extra_logging
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default0

    This variable can be used to enable recording in the MySQL error log of information specific to the NDB storage engine. It is normally of interest only when debugging NDB storage engine code.

    The default value is 0, which means that the only NDB-specific information written to the MySQL error log relates to transaction handling. If the value is greater than 0 but less than 10, NDB table schema and connection events are also logged, as well as whether or not conflict resolution is in use, and other NDB errors and information. If the value is set to 10 or more, information about NDB internals, such as the progress of data distribution among cluster nodes, is also written to the MySQL error log.

  • ndb_force_send

    Command-Line Format--ndb-force-send
    Option-File Formatndb_force_send
    Option Sets VariableYes, ndb_force_send
    Variable Namendb_force_send
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultTRUE

    Forces sending of buffers to NDB immediately, without waiting for other threads. Defaults to ON.

  • ndb_index_stat_cache_entries

    Command-Line Format--ndb_index_stat_cache_entries
    Option-File Formatndb_index_stat_cache_entries
     Permitted Values
    Typenumeric
    Default32
    Range0 .. 4294967295

    Sets the granularity of the statistics by determining the number of starting and ending keys to store in the statistics memory cache. Zero means no caching takes place; in this case, the data nodes are always queried directly. Default value: 32.

    Замечание

    If ndb_index_stat_enable is OFF, then setting this variable has no effect.

  • ndb_index_stat_enable

    Command-Line Format--ndb_index_stat_enable
    Option-File Formatndb_index_stat_enable
     Permitted Values
    Typeboolean
    DefaultON

    Use NDB index statistics in query optimization. Defaults to ON.

  • ndb_index_stat_update_freq

    Command-Line Format--ndb_index_stat_update_freq
    Option-File Formatndb_index_stat_update_freq
     Permitted Values
    Typenumeric
    Default20
    Range0 .. 4294967295

    How often to query data nodes instead of the statistics cache. For example, a value of 20 (the default) means to direct every 20th query to the data nodes.

    Замечание

    If ndb_index_stat_cache_entries is 0, then setting this variable has no effect; in this case, every query is sent directly to the data nodes.

  • ndb_join_pushdown

    Variable Namendb_join_pushdown
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean
    DefaultTRUE

    Added in MySQL Cluster NDB 7.2.0, this variable controls whether joins on NDB tables are pushed down to the NDB kernel (data nodes). Previously, a join was handled using multiple accesses of NDB by the SQL node; however, when ndb_join_pushdown is enabled, a pushable join is sent in its entirety to the data nodes, where it can be distributed among the data nodes and executed in parallel on multiple copies of the data, with a single, merged result being returned to mysqld. This can reduce greatly the number of round trips between an SQL node and the data nodes required to handle such a join.

    By default, ndb_join_pushdown is enabled.

    In order for a join to be pushable, it must meet the following conditions:

    1. Only columns can be compared, and all columns to be joined must use exactly the same data type.

      This means that expressions such as t1.a = t2.a + constant cannot be pushed down, and that (for example) a join on an INT column and a BIGINT column also cannot be pushed down.

    2. Queries referencing BLOB or TEXT columns are not supported.

    3. Explicit locking is not supported; however, the NDB storage engine's characteristic implicit row-based locking is enforced.

      This means that a join using FOR UPDATE cannot be pushed down.

    4. In order for a join to be pushed down, child tables in the join must be accessed using one of the ref, eq_ref, or  const access methods, or some combination of these methods.

      Outer joined child tables can only be pushed using eq_ref.

      If the root of the pushed join is an eq_ref or const, only child tables joined by eq_ref can be appended. (A table joined by ref is likely to become the root of another pushed join.)

      If the query optimizer decides on Using join cache for a candidate child table, that table cannot be pushed as a child. However, it may be the root of another set of pushed tables.

    5. Joins referencing tables explicitly partitioned by [LINEAR] HASH, LIST, or RANGE currently cannot be pushed down.

    You can see whether a given join can be pushed down by checking it with EXPLAIN; when the join can be pushed down, you can see references to the pushed join in the Extra column of the output, as shown in this example:

    mysql> EXPLAIN
        ->     SELECT e.first_name, e.last_name, t.title, d.dept_name
        ->         FROM employees e
        ->         JOIN dept_emp de ON e.emp_no=de.emp_no
        ->         JOIN departments d ON d.dept_no=de.dept_no
        ->         JOIN titles t ON e.emp_no=t.emp_no\G
    *************************** 1. row ***************************
               id: 1
      select_type: SIMPLE
            table: d
             type: ALL
    possible_keys: PRIMARY
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 9
            Extra: Parent of 4 pushed join@1
    *************************** 2. row ***************************
               id: 1
      select_type: SIMPLE
            table: de
             type: ref
    possible_keys: PRIMARY,emp_no,dept_no
              key: dept_no
          key_len: 4
              ref: employees.d.dept_no
             rows: 5305
            Extra: Child of 'd' in pushed join@1
    *************************** 3. row ***************************
               id: 1
      select_type: SIMPLE
            table: e
             type: eq_ref
    possible_keys: PRIMARY
              key: PRIMARY
          key_len: 4
              ref: employees.de.emp_no
             rows: 1
            Extra: Child of 'de' in pushed join@1
    *************************** 4. row ***************************
               id: 1
      select_type: SIMPLE
            table: t
             type: ref
    possible_keys: PRIMARY,emp_no
              key: emp_no
          key_len: 4
              ref: employees.de.emp_no
             rows: 19
            Extra: Child of 'e' in pushed join@1
    4 rows in set (0.00 sec)
    
    Замечание

    If inner joined child tables are joined by ref, and the result is ordered or grouped by a sorted index, this index cannot provide sorted rows, which forces writing to a sorted tempfile.

    Two additional sources of information about pushed join performance are available:

    1. The status variables Ndb_pushed_queries_defined, Ndb_pushed_queries_dropped, Ndb_pushed_queries_executed, and Ndb_pushed_reads (all introduced in MySQL Cluster NDB 7.2.0).

    2. The counters in the ndbinfo.counters table that belong to the DBSPJ kernel block. (These counters and the DBSPJ block were also introduced in MySQL Cluster NDB 7.2.0). See Section 16.5.9.3, “The ndbinfo counters Table”, for information about these counters. See also The DBSPJ Block, in the MySQL Cluster API Developer Guide.

  • ndb_log_apply_status

    Command-Line Format--ndb-log-apply-status
    Option-File Formatndb-log-apply-status
    Option Sets VariableYes, ndb_log_apply_status
    Variable Namendb_log_apply_status
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean
    DefaultOFF

    A read-only variable which shows whether the server was started with the --ndb-log-apply-status option.

  • ndb_log_bin

    Command-Line Format--ndb-log-bin={1|0}
    Option Sets VariableYes, ndb_log_bin
    Variable Namendb_log_bin
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultON

    Causes updates to NDB tables to be written to the binary log. Setting this variable has no effect if binary logging is not already enabled for the server using log_bin. ndb_log_bin defaults to 1 (ON); normally, there is never any need to change this value in a production environment.

  • ndb_log_binlog_index

    Command-Line Format--ndb-log-binlog-index={1|0}
    Option Sets VariableYes, ndb_log_binlog_index
    Variable Namendb_log_binlog_index
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultON

    Causes a mapping of epochs to positions in the binary log to be inserted into the ndb_binlog_index table. Setting this variable has no effect if binary logging is not already enabled for the server using log_bin. (In addition, ndb_log_bin must not be disabled.) ndb_log_binlog_index defaults to 1 (ON); normally, there is never any need to change this value in a production environment.

  • ndb_log_transaction_id

    Version Introduced5.5.15-ndb-7.2.1
    Variable Namendb_log_transaction_id
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typeboolean
    DefaultOFF

    This read-only, Boolean system variable shows whether a slave mysqld writes NDB transaction IDs in the binary log (required to use “active-active” MySQL Cluster Replication with NDB$EPOCH_TRANS() conflict detection). To change the setting, use the --ndb-log-transaction-id option.

    ndb_log_transaction_id is available in MySQL Cluster NDB 7.2.1 and later. It is not supported in mainline MySQL Server 5.5.

    For more information, see Section 16.6.11, “MySQL Cluster Replication Conflict Resolution”.

  • ndb_optimized_node_selection

    Command-Line Format--ndb-optimized-node-selection4.1.9-5.1.22-ndb-6.33 
    --ndb-optimized-node-selection=#
    Option-File Formatndb_optimized_node_selection
     Permitted Values
    Typeboolean
    DefaultON
     Permitted Values
    Typenumeric
    Default3
    Range0 .. 3

    There are two forms of optimized node selection, described here:

    1. The SQL node uses promixity to determine the transaction coordinator; that is, the “closest” data node to the SQL node is chosen as the transaction coordinator. For this purpose, a data node having a shared memory connection with the SQL node is considered to be “closest” to the SQL node; the next closest (in order of decreasing proximity) are: TCP connection to localhost; SCI connection; TCP connection from a host other than localhost.

    2. The SQL thread uses distribution awareness to select the data node. That is, the data node housing the cluster partition accessed by the first statement of a given transaction is used as the transaction coordinator for the entire transaction. (This is effective only if the first statement of the transaction accesses no more than one cluster partition.)

    This option takes one of the integer values 0, 1, 2, or 3. 3 is the default. These values affect node selection as follows:

    • 0: Node selection is not optimized. Each data node is employed as the transaction coordinator 8 times before the SQL thread proceeds to the next data node.

    • 1: Proximity to the SQL node is used to determine the transaction coordinator.

    • 2: Distribution awareness is used to select the transaction coordinator. However, if the first statement of the transaction accesses more than one cluster partition, the SQL node reverts to the round-robin behavior seen when this option is set to 0.

    • 3: If distribution awareness can be employed to determine the transaction coordinator, then it is used; otherwise proximity is used to select the transaction coordinator. (This is the default behavior.)

  • ndb_report_thresh_binlog_epoch_slip

    Command-Line Format--ndb_report_thresh_binlog_epoch_slip
    Option-File Formatndb_report_thresh_binlog_epoch_slip
     Permitted Values
    Typenumeric
    Default3
    Range0 .. 256

    This is a threshold on the number of epochs to be behind before reporting binary log status. For example, a value of 3 (the default) means that if the difference between which epoch has been received from the storage nodes and which epoch has been applied to the binary log is 3 or more, a status message will be sent to the cluster log.

  • ndb_report_thresh_binlog_mem_usage

    Command-Line Format--ndb_report_thresh_binlog_mem_usage
    Option-File Formatndb_report_thresh_binlog_mem_usage
     Permitted Values
    Typenumeric
    Default10
    Range0 .. 10

    This is a threshold on the percentage of free memory remaining before reporting binary log status. For example, a value of 10 (the default) means that if the amount of available memory for receiving binary log data from the data nodes falls below 10%, a status message will be sent to the cluster log.

  • slave_allow_batching

    Command-Line Format--slave-allow-batching
    Option-File Formatslave_allow_batching
    Option Sets VariableYes, slave_allow_batching
    Variable Nameslave_allow_batching
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    Defaultoff

    Whether or not batched updates are enabled on MySQL Cluster replication slaves.

    This variable is available beginning with MySQL Cluster NDB 6.2.3. Currently, it is available for mysqld only as supplied with MySQL Cluster or built from the MySQL Cluster sources. For more information, see Section 16.6.6, “Starting MySQL Cluster Replication (Single Replication Channel)”.

  • ndb_table_no_logging

    Variable Namendb_table_no_logging
    Variable ScopeSession
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultFALSE

    When this variable is set to ON or 1, it causes NDB tables not to be checkpointed to disk. More specifically, this setting applies to tables which are created or altered using ENGINE NDB when ndb_table_no_logging is enabled, and continues to apply for the lifetime of the table, even if ndb_table_no_logging is later changed. Suppose that A, B, C, and D are tables that we create (and perhaps also alter), and that we also change the setting for ndb_table_no_logging as shown here:

    SET @@ndb_table_no_logging = 1;
    
    CREATE TABLE A ... ENGINE NDB;
    
    CREATE TABLE B ... ENGINE MYISAM;
    CREATE TABLE C ... ENGINE MYISAM;
    
    ALTER TABLE B ENGINE NDB;
    
    SET @@ndb_table_no_logging = 0;
    
    CREATE TABLE D ... ENGINE NDB;
    ALTER TABLE C ENGINE NDB;
    
    SET @@ndb_table_no_logging = 1;

    After the previous sequence of events, tables A and B are not checkpointed; A was created with ENGINE NDB and B was altered to use NDB, both while ndb_table_no_logging was enabled. However, tables C and D are logged; C was altered to use NDB and D was created using ENGINE NDB, both while ndb_table_no_logging was disabled. Setting ndb_table_no_logging back to 1 or ON does not cause table C or D to be checkpointed.

    Замечание

    ndb_table_no_logging has no effect on the creation of NDB table schema files; to suppress these, use ndb_table_temporary instead.

  • ndb_table_temporary

    Variable Namendb_table_temporary
    Variable ScopeSession
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultFALSE

    When set to ON or 1, this variable causes NDB tables not to be written to disk: This means that no table schema files are created, and that the tables are not logged.

    Замечание

    Setting this variable currently has no effect in MySQL Cluster NDB 7.0 and later. This is a known issue; see BUG#34036.

  • ndb_use_copying_alter_table

    Variable Namendb_use_copying_alter_table
    Variable ScopeGlobal, Session
    Dynamic VariableNo

    Forces NDB to use copying of tables in the event of problems with online ALTER TABLE operations. The default value is OFF.

  • ndb_use_exact_count

    Variable Namendb_use_exact_count
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultON

    Forces NDB to use a count of records during SELECT COUNT(*) query planning to speed up this type of query. The default value is ON. For faster queries overall, disable this feature by setting the value of ndb_use_exact_count to OFF.

  • ndb_use_transactions

    Command-Line Format--ndb_use_transactions
    Option-File Formatndb_use_transactions
    Variable Namendb_use_transactions
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultON

    You can disable NDB transaction support by setting this variable's values to OFF (not recommended). The default is ON.

  • transaction_allow_batching

    Variable Nametransaction_allow_batching
    Variable ScopeSession
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultFALSE

    When set to 1 or ON, this variable enables batching of statements within the same transaction. To use this variable, autocommit must first be disabled by setting it to 0 or OFF; otherwise, setting transaction_allow_batching has no effect.

    It is safe to use this variable with transactions that performs writes only, as having it enabled can lead to reads from the “before” image. You should ensure that any pending transactions are committed (using an explicit COMMIT if desired) before issuing a SELECT.

    Important

    transaction_allow_batching should not be used whenever there is the possibility that the effects of a given statement depend on the outcome of a previous statement within the same transaction.

    This variable is currently supported for MySQL Cluster only.

The system variables in the following list all relate to the ndbinfo information database.

  • ndbinfo_database

    Variable Namendbinfo_database
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typestring
    Defaultndbinfo

    Shows the name used for the NDB information database; the default is ndbinfo. This is a read-only variable whose value is determined at compile time; you can set it by starting the server using --ndbinfo-database=name, which sets the value shown for this variable but does not actually change the name used for the NDB information database.

  • ndbinfo_max_bytes

    Command-Line Format--ndbinfo-max-bytes=#
    Option Sets VariableYes, ndbinfo_max_bytes
    Variable Namendbinfo_max_bytes
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default0

    Used in testing and debugging only.

  • ndbinfo_max_rows

    Command-Line Format--ndbinfo-max-rows=#
    Option Sets VariableYes, ndbinfo_max_rows
    Variable Namendbinfo_max_rows
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typenumeric
    Default10

    Used in testing and debugging only.

  • ndbinfo_show_hidden

    Command-Line Format--ndbinfo-show-hidden={0|1}
    Option Sets VariableYes, ndbinfo_show_hidden
    Variable Namendbinfo_show_hidden
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    Defaultno

    Whether or not the ndbinfo database's underlying internal tables are shown in the mysql client. The default is OFF.

  • ndbinfo_table_prefix

    Command-Line Format--ndbinfo-table-prefix=name
    Option Sets VariableYes, ndbinfo_table_prefix
    Variable Namendbinfo_table_prefix
    Variable ScopeGlobal, Session
    Dynamic VariableYes
     Permitted Values
    Typestring
    Defaultndb$

    The prefix used in naming the ndbinfo database's base tables (normally hidden, unless exposed by setting ndbinfo_show_hidden). This is a read-only variable whose default value is “ndb$”. You can start the server with the --ndbinfo-table-prefix option, but this merely sets the variable and does not change the actual prefix used to name the hidden base tables; the prefix itself is determined at compile time.

  • ndbinfo_version

    Variable Namendbinfo_version
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typestring
    Default

    Shows the version of the ndbinfo engine in use; read-only.

  • ndb_log_empty_epochs

    Command-Line Format--ndb-log-empty-epochs
    Option-File Formatndb_log_empty_epochs
    Variable Namendb_log_empty_epochs
    Variable ScopeGlobal
    Dynamic VariableYes
     Permitted Values
    Typeboolean
    DefaultOFF

    When this variable is set to 0, epoch transactions with no changes are not written to the binary log, although a row is still written even for an empty epoch in ndb_binlog_index.

  • server_id_bits

    Command-Line Format--server-id-bits=#
    Option-File Formatserver-id-bits
    Option Sets VariableYes, server_id_bits
    Variable Nameserver_id_bits
    Variable ScopeGlobal
    Dynamic VariableNo
     Permitted Values
    Typenumeric
    Default32
    Range7 .. 32

    The effective value of server_id if the server was started with the --server-id-bits option set to a nondefault value.

    If the value of server_id greater than or equal to 2 to the power of server_id_bits, mysqld refuses to start.

    This system variable is supported only by MySQL Cluster. server_id_bits is not supported by the standard MySQL Server.

16.3.4.4. MySQL Cluster Status Variables

This section provides detailed information about MySQL server status variables that relate to MySQL Cluster and the NDB storage engine. For status variables not specific to MySQL Cluster, and for general information on using status variables, see Section 5.1.5, “Server Status Variables”.